Adenitis of the sebaceous glands in dogs: an “ugly” skin disease. Tumors of the perianal glands (perianal adenomas) Sebaceous gland hyperplasia in dogs
Inflammation of the sebaceous glands is not a very common skin disease; It is most often diagnosed in dogs. However, inflammation of the sebaceous glands has been described in other animal species, including cats and rabbits. There are few reports of a similar disease in humans. The most important feature of this disease is infiltrative inflammation combined with destruction of the sebaceous glands.
Sebaceous glands are holocrine alveolar glandular formations in mammals whose skin is covered with hair, connecting to the hair follicles. These glands open through a duct in the infundibulum of the hair follicle (infundibular-sebaceous junction). Their oily secretion (sebum) forms an emulsion with the secretion of the sweat glands on the surface of the epidermis and is distributed over the surface of the stratum corneum of the skin. The main function of this emulsion is to maintain the elasticity and softness of the skin, prevent the loss of moisture and, thus, maintain an adequate level of skin hydration. The emulsion also functions as a physical and chemical barrier, preventingallowing pathogenic microorganisms to penetrate into deeper tissues of the bodyov. The chemical composition of the secretion of the sebaceous glands varies among different species of mammals. In dogs and cats, surface lipids predominate in it - especially free cholesterol, sterol esters and wax acid diesters, while triglycerides and squalene are significantly less than in the secretion of the human sebaceous glands.
Etiology
Inflammation of the sebaceous glands in a narrow interpretation is a rare idiopathic skin disease. It often develops in Akita Inu and Standard Poodle dogs. There is an assumption that in these dog breeds the tendency to this disease is inherited in an autosomal recessive manner. In addition, inflammation of the sebaceous glands is also common in the German Shepherd, Vizsla (Hungarian Shorthaired Pointer), Hovawart, a number of other breeds and cross-bred dogs. The pathogenesis of the disease is still unknown. There have been suggestions that inflammation of the sebaceous glands occurs as a result of:
- primary structural defects of the sebaceous glands and their ducts, causing the leakage of secretions, to which the body, in turn, reacts as if it were a foreign body;
- failure of lipid metabolism, which affects the formation of sebaceous gland secretions;
- as well as disturbances of primary keratinization, leading to inflammation and atrophy of the sebaceous glands and their ducts.
Immunohistochemical studies of the sebaceous glands have shown that mainly the cell population in the inflamed sebaceous glandsconstitute dendritic cells of the major histocompatibility complex class II, as well as CD4+ and CD8+ T lymphocytes, which serve as effector cells in cell-mediated autoimmune diseases. B-lymphocytes and autoantibodies to sebaceous gland antigens were not detected during their inflammation. The assumption that inflammation of the sebaceous glands is a cell-mediated autoimmune disease is supported by the fact that the concentration of T-lymphocytes and macrophages decreases during immunomodulatory therapy with cyclosporine.
Secondary destruction of the sebaceous glands, which is accompanied by clinical changes characteristic of hyperkeratosis, can develop with generalized demodicosis, leishmaniasis, severe histiocytic, granulomatous folliculitis and other diseases.
Clinical signs
Most often, adult dogs (young and middle-aged) suffer from inflammation of the sebaceous glands, regardless of gender predisposition. Variations in clinical signs, degree of dissemination of lesions, and inflammation of the sebaceous glands occur widely among dogs of different breeds and different representatives of the same breed. This disease has a common characteristic feature of clinical manifestations: silvery-white dandruff and skin scales attached to the hair (called follicular casts) appear on the skin of the animal. Most likely, such follicular discharge is the result of an insufficient amount of secretion from the sebaceous glands entering the funnel (in which, in long-haired dog breeds, keratinization of the outer sheath of the hair root occurs) of the hair follicles. Inflammation of the sebaceous glands has been most studied in the Samoyed husky, Akita Inu and standard poodle. The first sign of the disease in these breeds is the appearance of sheet-like keratinized discharges from the hair follicles and the enveloping of the hair shaft with a durable layer of keratinized tissue residues. Removing the hair allows you to notice that the hair roots are surrounded by follicular emissions. The spread of inflammation in a standard poodle often begins in the dorsal part of the muzzle and temporal region, after which the disease spreads to the dorsal part of the neck and chest. Dogs of the Hovawart and Akita Inu breeds have more intense, symmetrical, numerous foci of alopecia. A characteristic feature of the pathological process is dullness and brittleness of the dog’s fur.
Lesions appear on the head, ears, dorsal surface of the neck, tail, and then spread along the midline of the animal’s body along its dorsal side. This stage is characterized by not very pronounced skin itching. As the disease progresses, it can become generalized with complications of secondary bacterial folliculitis, which increases skin itching. This stage of the pathological process is accompanied by the appearance of an unpleasant odor
In Hovawarts and Belgian Shepherds, this disease often has concomitant inflammation of the outer ear, in which dry, sticky skin scales accumulate in the ear canal. The duration of the clinically evident stage of the disease may vary. There is no dependence of inflammation of the sebaceous glands on seasonality.
Inflammation of the sebaceous glands manifests itself differently in short-haired dogs. There is the formation of nodules with arched or merging areas of baldness, which give the coat a moth-eaten appearance. Localization of numerous scattered skin scales occurs mainly on the body of the animal. In addition, cyclical swelling of the muzzle appears, which gives veterinarians grounds to classify this form of inflammation of the sebaceous glands as an independent disease.
Diagnostics
The diagnosis of “inflammation of the sebaceous glands” can be established based on the results of a clinical examination of the animal and medical history. In differential diagnosis, seborrheic dermatitis, primary seborrhea, dermatitis as a result of the body's reaction to vitamin A, a generalized form of demodicosis, and dermatomycosichthyosis are excluded. It should be noted that inflammation of the sebaceous glands can occur in a nodular form (with the formation of nodules), as a consequence of the development of bacterial folliculitis and furunculosis. In order to establish a final diagnosis, a skin biopsy is performed with a histological examination of the resulting material. Pathohistological changes in the skin of dogs with inflammation of the sebaceous glands are varied and depend on the duration of the disease. The early stage of inflammation of the sebaceous glands in the narrowed part of the hair follicles (isthmus) is characterized by the appearance of individual perifollicular cells of the inflammatory infiltrate. Then a granulomatous, pyogranulomatous or nodular inflammatory reaction develops around the sebaceous glands. Sebocytes (secretory cells of the sebaceous glands) are destroyed, as evidenced by histological sections of skin biopsies. The spread of the inflammatory process to the apocrine sweat glands is blocked due to blockage of the hair follicles. Inflammatory infiltrates consist of lymphocytes, neutrophils and histiocytes. The ducts of the hair follicles of dogs of long-haired breeds with this disease are usually blocked, and pronounced orthokeragosic hyperkeratosis appears. In dogs of short-haired breeds, hyperkeratotic changes are not as severe. The full development of the pathological process is characterized by the destruction of the sebaceous glands, and there are fewer foci of the inflammatory reaction of the skin. Telogenization or atrophy of hair follicles occurs. The presence of a secondary staphylococcal infection contributes to purulent folliculitis or furunculosis.
Treatment
Since inflammation of the sebaceous glands does not have a significant impact on the overall health of the animal, unless there are complications of secondary pyoderma, which can be avoided with appropriate therapy. When determining treatment methods and choosing medications, they strive to balance the recommendations of specialists and financial costs with the safety, simplicity and ease of performing treatment procedures. The goal of treating inflammation of the sebaceous glands is to restore the barrier function of the skin, for which excess exfoliated remains of skin tissue are removed, preventive measures are taken for secondary bacterial infections, which help improve the quality of the coat and restore hair growth. Since there are no effective treatments for inflammation of the sebaceous glands, long-term treatment is necessary to improve the clinical condition. The literature provides various treatment regimens for inflammation of the sebaceous glands.
An effective way to treat inflammation of the sebaceous glands in dogs is the use of shampoos with an antiseborrheic effect, followed by rubbing oils into the skin, as well as the use of additional skin treatment with moisturizing sprays in between the above procedures. The scheme for such local treatment of inflammation of the sebaceous glandsproceeds as follows:
Stage 1:
- The dog's skin is treated with a combined shampoo with sulfur and salicylic acid;
- The foamed shampoo is left on the animal’s skin for at least 10 minutes;
- The animal's skin is massaged for a specified period of time with a soft brush to remove excess skin flakes;
- The shampoo is thoroughly washed off and the skin is dried with a towel.
Stage 2: A preparation based on light mineral oil (for example, baby skin oil) is rubbed into the dog’s skin and coat. The animal remains in this form for several hours.
Stage 3: The oil is removed by briefly washing it with an antibacterial shampoo with weak cleaning properties.
At the final stage of therapeutic treatment, a conditioner or a mixture of propylene glycol and water (50-70% propylene glycol) is applied to moisturize. This mixture can be periodically applied to the animal’s skin, alternately vigorously rubbing the oil into it.
Treatment according to this scheme at the beginning of the course is carried out once or twice a week, and after the dog’s condition improves, the frequency of treatments is reduced to once every two weeks. Systemic therapy is necessary to stop the further development of the inflammatory reaction of the skin and stimulate the differentiation of keratinocytes.
It has been noted that the use of corticosteroid drugs in doses that ensure their anti-inflammatory effect and immunosuppressive effect in the treatment of some short-haired dog breeds provides a positive therapeutic effect only in a few cases.
Synthetic retinoids have anti-inflammatory properties, accelerate the differentiation of keratinocytes and suppress the secretory function of the sebaceous glands. An effective positive effect of these drugs was noted in the treatment of inflammation of the sebaceous glands in Vizsla dogs, unlike other breeds. Synthetic retinoids are prescribed to dogs orally at a dose of 1 mg per 1 kg of body weight 1-2 times a day. In most cases, an improvement in the patient's clinical condition is noted within 6 weeks of treatment, after which the frequency of taking synthetic retinoids is reduced.
In one experiment, dogs suffering from inflammation of the sebaceous glands were given vitamin A orally in doses of 1 OOO to 3 OOO international units twice a day. Improvement in the clinical condition of patients was noted within three months. During long-term use of corticosteroids and retinoids, clinicians have noted side effects in dogs. That is why, in case of inflammation of the sebaceous glands, these drugs should not be chosen as therapeutic drugs if they do not provide complete recovery.
Giving dogs high doses of fish oil orally reduces the severity of clinical signs of inflammation of the sebaceous glands.
Cyclosporine is highly effective at a dose of 5 mg per 1 kg of animal body weight once a day. Among the advantages of cyclosporine ego safety and good tolerability, it effectively reduces the intensity of the perifollicular inflammatory infiltration process, which contributes to the destruction of the sebaceous glands, and increases the relative number of hair follicles with the sebaceous glands. Experience shows that treatment with this drug has the greatest effect at the early stage of the disease, during the intensive development of the inflammatory reaction. In cases of chronic disease, with atrophy and disappearance of all sebaceous glands, and the cessation of the inflammatory reaction, such treatment is less effective. This suggests that only those sebaceous glands that have not been completely destroyed have the ability to regenerate.
In the first four months of this treatment, in combination with additional local treatments, there is a decrease in the intensity of the formation of skin scales and a decrease in alopecia, at which time the general clinical condition of the dog and the quality of the coat are significantly improved. You can continue using cyclosporine less often. This drug also has the property of inducing hair growth, due to which it can also promote healing. Preliminary results from an experiment (not yet published) show that improvement in the clinical condition of dogs with inflamed sebaceous glands is accelerated by topical treatments. Interestingly, intensive topical treatment (such as the one described above) appears to be as clinically effective as systemic cyclosporine treatment. Realizing that an animal with this pathology has to be treated for life, it is important for the doctor to know for himself and convince the owner of the sick dog that treating inflammation of the sebaceous glands using local therapy does not require the same amount of time, effort and expense as treating possible complications . In cases of long-term use of glucocorticoid drugs in high doses, severe side effects often develop.
Tumors (neoplasms) of animals and humans have been known since ancient times.
“Life is short, the path of art is long, opportunity is fleeting,
experience is unreliable, judgment is difficult.
Therefore, not only the doctor himself must be ready to do everything,
what is required of him, but also the patient and those around him,
and all external circumstances should facilitate the doctor in his activities.”
Hippocrates
Whether we observe certain phenomena or not depends on the theory,
which we will use.
Rudolf Virchow
Tumors (neoplasms) of animals and humans have been known since ancient times. A description of individual forms of tumors can be found in Hippocrates. And his famous words: “Life is short, the path of art is long, opportunity is fleeting, experience is unreliable, judgment is difficult. Therefore, not only the doctor himself must be ready to do everything that is required of him, but also the patient, those around him, and all external circumstances must contribute to the doctor in his activities,” which perfectly fits the entire history of the development of knowledge about oncological diseases and their diagnosis and therapy.
New bone formations have been found on mummies of ancient Egypt and remains of more ancient origin. Surgical methods for the treatment of tumors were used in medical schools of ancient Egypt, China, India, the Incas of Peru, etc. However, despite significant interest in the issue of the occurrence and growth of tumors, despite numerous attempts to treat them, the level of medical science for a number of centuries has not allowed for a more in-depth study of these diseases. This became possible only after the invention of the microscope and the development of pathological anatomy, especially after the work of Rudolf Virchow on cellular pathology, i.e. in the second half of the 19th century. The theory of cellular pathology divided medicine into the pre-Virchow period and the post-Virchow period; it was Virchow who introduced into medicine such terms as “thrombosis”, “embolism”, “amyloid degeneration”, “leukemia”, proliferation) 1855. It was Virchow who forced all doctors to look at the world with different eyes , armed with a microscope, and proposed to perceive the pathology of the body through the pathology of an individual cell. Rudolf Virchow said whether we observe certain phenomena or not depends on the theory we use.
Experimental studies on animals were extremely important for the development of oncology.
The founder of experimental oncology is the veterinarian Mstislav Aleksandrovich Novinsky, who in 1876 was the first in the world to successfully transplant malignant tumors from adult dogs to puppies.
Erlich and Petrov proved the autonomy of tumors and the gradual increase in their malignancy. Many morphological and biochemical features of tumor tissue were studied using transplanted neoplasms.
P. Pott described skin cancer in chimney sweeps, and proved its origin as a result of long-term contamination with coal distillation products, soot, and smoke particles.
Yamagiwa and Ichikawa (1915-1916) obtained experimental skin cancer in rabbits by smearing the skin with coal tar.
Higuera, Cook and their co-workers (1932, 1933) found that the active carcinogenic agent of various resins is polycyclic aromatic hydrocarbons (benzapyrene).
Rouso (1910, 1911) discovered the viral nature of some chicken sarcomas. These works formed the basis of the viral concept of cancer etiology and served as the beginning of many studies in this direction, which led to the discovery of a number of viruses that cause tumors in animals (Shope rabbit papilloma virus, 1933; Bitner mouse mammary cancer virus, 1936; Gross mouse leukemia viruses , 1951; Stewart’s “polyoma” virus, 1957, etc.).
In 1910 The first manual in Russia by N. N. Petrov, “The General Doctrine of Tumors,” was published.
In the USSR, using radioactive substances and carcinogenic hydrocarbons, for the first time in the world, experimental malignant tumors were obtained in monkeys.
In 1937, for the first time in the world, the possibility of obtaining tumors in animals was proven as a result of the introduction of extracts from the tissues of people who died of cancer, and thus the foundations of ideas about endogenous blastomogenic substances were laid (L. M. Shabad).
There is no reliable information on the incidence of tumors in domestic animals. This is explained by the fact that until very recently, insufficient attention was paid to tumor statistics in veterinary science. While the issues of accounting for the incidence of human tumors and cancer mortality in medicine have been developed quite fully, the statistics of tumors in veterinary medicine are based on random material and often do not correspond to the true state of the issue. Data on the frequency of neoplasms in animals are based primarily on sectional material.
Attempts to present a statistical review of animal tumors are associated with great difficulties, because the initial data of such a review are very incomplete and contradictory.
It is enough to remember the 50-60s of the last century, when the experts’ belief that animals do not suffer from cancer at all was still strong.
Skin tumors are most common in dogs, and among all animals there is the most historical and statistical data on them.
- Schütz (1936) provides data for 5 years.
- 55,389 dogs were examined – malignant tumors were detected in 2,136 (0.56%)
- Same author for 14 years
- Autopsied 1241 dogs, found cancer in 5% of dogs
- Withers (1939)
- Conducted 396 autopsies of dogs that died for unknown reasons, found carcinomas and other tumors in 53 dogs (13%)
- Cotchin (1954)
- Published data in which he indicated that among dogs in the north London area, cancer is 15%.
Richard A.S. White (2003) reported that more than half of dogs over 10 years of age die from cancer.
The need for the development of clinical oncology of small domestic animals is very great and it is not clear why veterinary specialists ignore cancer when improving their qualifications. Suffice it to remember that in veterinary universities there is still no separate discipline of oncology, much less its specializations - clinical oncology, cyto-oncology and histo-oncology. In Europe, the first textbook on veterinary oncology was written by Larry Owen 20 years ago, and today it is the most developed discipline in Western countries.
Today, the situation with veterinary oncology in Russia is deplorable; there is no independent course in veterinary oncology in higher educational institutions. There are no textbooks, there are only individual monographs. There is no discipline “Clinical Cytology”.
According to my own observations in veterinary clinics in Russia, and even in the most advanced ones, only a few specialists know the main clinical method for diagnosing tumors - cytological examination. And among all kinds of veterinary societies, such as cardiology, visual diagnostics and others, there is no Russian Oncological Society. But the situation is gradually changing, translated printed publications have appeared, many authors’ own experience is gradually accumulating, and we will try to share some of our experiences and will be glad if they are of benefit to you.
So, cancer as a cause of death ranks second in humane medicine.
In dogs, having supplanted infectious diseases, it firmly occupies first place, and at present there is no tendency for the situation to change for the better in the near future.
According to the modern theory of oncogenesis, all tumors are monoclonal, that is, they originate from one single cell, only then, in the already grown clone of cells, repeated mutations occur, which lead to cellular atypia. As a result of repeated mutations, a rapid selection of cells occurs (such selection of cells follows the principle of natural selection, and our native cells here can give a head start to tenacious bacteria), capable of escaping from the immune control of the body, capable of more rapid reproduction, capable of quickly penetrating into surrounding tissues and capture new territories, since these cells no longer obey the general rules of the body, but only the general biological rule, which is more ancient and more reliable.
AND THIS RULE SAYS: “SURVIVE AND REPRODUCT”
As soon as the connection between the cell and the organism is lost, as soon as the cell ceases to feel like it is part of the organism, and the organism loses control over this cell, just think about it, over one single cell, the matter ends with the death of the entire organism. This is the price of violating all-organismal discipline; violating it by one single cell among many billions leads to fatal consequences both for the body and for the “lost soul.”
Morphologists or histologists believe that tumors can be divided into three groups regarding their differentiation. Differentiation is the degree of cell maturity, while differentiated tumor cells are similar to the original cells of the tissues from which they arise, and are not similar to young cells (undifferentiated). There are highly differentiated tumors. Their cells strongly resemble healthy ones (which is why the result of a morphological study is often inaccurate). Moderately differentiated tumors are less similar to the cells of the tissues from which they arose. The cells of these tumors are younger and have fewer features of their parent cells. Poorly differentiated cells resemble very little the cells of the tissues from which they originated. These cells are very young and more similar to blast cells, the cells from which all tissues in embryos are formed. These cells do not have specific (specialized) structures characteristic of mature cells. Since tumor tissue undergoes selection for cell survival, these cells, in the process of such evolution, lose all the specialized organelles necessary to perform the functions necessary for the body, the functions for which they were “created.” For example, keratinocytes (superficial skin cells) lose their ability to keratinize, secretory cells lose their ability to secrete, and so on. But it’s understandable why cells work for the benefit of the body; they now have their own “higher goal”, to survive and multiply, multiply and multiply.
It is believed that highly differentiated tumors are less aggressive than poorly differentiated ones (but are also less treatable). And the point is not that they cannot be killed, but the point is that they are more similar to healthy cells, and the more similar they are, the fewer drugs that could act on tumor cells and not act on healthy ones.
As cancer cells are selected and rejuvenated, their sensitivity to chemotherapy and radiation increases. But the trouble is, at the same time the rate of their reproduction and selection is increasing. Which leads to their rapid departure not only from the body’s immunological control, but also from therapeutic control. Such a tumor becomes incurable.
Among all skin tumors in dogs and cats, the following groups of tumors are distinguished: epithelial tumors, melanocytic tumors, mast cell tumors, mesenchymal tumors, tumors of nervous tissue.
In this work, we will devote more attention to epithelial tumors in dogs (cats), with special attention to skin cancer in dogs (cats).
Today it is customary to distinguish the following epithelial tumors in dogs (cats): squamous cell papilloma, basal cell papilloma, basal cell carcinoma, squamous cell carcinoma, epithelial cyst, tumors of the skin appendages (tumors of the sebaceous glands and atheromas, tumors of the sweat glands, tumors of the hair follicles, tumors of the mammary glands ).
Squamous cell papilloma is one of the most common tumors in dogs. It is believed that these tumors, according to their etiology, can be spontaneous or induced by viruses. In dogs, squamous cell papillomas are most often caused by viruses and in this case are multiple in nature. Spontaneous ones develop in places where the skin is injured, for example on the elbows, crowns and protrusions of the hock joints. Typical squamous cell papillomas in dogs are found at the border of the mucous membranes and skin.
In puppies and young dogs, they are characterized primarily by viral etiology and, accordingly, the multiplicity of lesions. Therefore, in the age period from 2 months to 1.5 years, it is more correct to talk about papillomatosis. They are localized mainly in the area of the anterior third of the oral cavity, but the mucous membranes of the genital organs and even the skin can be affected. With significant spread, papillomas can cover the entire surface of the oral mucosa. After surgical intervention, as a rule, they recur, tend to spread to neighboring areas of the mucous membrane, sometimes affecting the area of the pharynx, vocal cords and even trachea, causing difficulty breathing. The ability to disperse after surgical removal is often regarded as implantation and is associated with the viral nature of the tumor. During puberty, they sometimes undergo spontaneous regression
Macroscopically, they have the appearance of warty formations of pink or bright red color with a fine-grained or finely lobed surface, sitting on a narrow base or on a stalk. They have a soft consistency, are easily injured and bleed, and can be removed without much effort.
Papillomas that occur in adult dogs are usually single. Multiple papillomas of adult animals are often a continuation of recurrent juvenile viral papillomatosis. There are known observations of implantation relapses after surgical removal.
A cytological examination of scrapings from the surface of papillomas reveals ordinary flat cells lying in random layers.
Squamous cell papillomas of dogs in histological examination have the structure of soft papillomas formed by papillary growths of multilayered squamous highly differentiated epithelium, sometimes with a tendency to keratinization. As it spreads to the pharynx and trachea, the character of the epithelium lining the papillae may change towards transitional and respiratory cancer with small areas of mucous secretion. The stroma of the papillae is represented by loose, soft fibrous connective tissue and is well vascularized. Lymphoid-plasmacytic infiltrates and accumulations of mast cells along the vessels are often found. During the period of active growth, they have a wide layer of basal cells with high mitotic activity and are classified as proliferating. However, malignancy of papillomas in puppies is not observed.
Macroscopically and microscopically, single papillomas in adult dogs have the character of solid papillomas, representing growths of stratified squamous keratinized epithelium covering papillae of dense connective tissue with a small number of vessels. The hyperkeratotic variant of papilloma is called white papilloma because of the white color of the surface of the tumor, caused by excess stratum corneum. Papillomas of adult dogs, according to various authors, become malignant in 4-14% of cases. The most frequently malignant lesions are white papillomas and papillomas with signs of submerged growth. Malignization is preceded by dysplastic changes in the epithelium in the form of a violation of the stratification of the appearance of areas of pathological keratinization, an increase in mitotic activity with fission figures in the middle and upper parts of the spinous layer.
Basal cell papilloma (papilloma basocellulare) synonyms (seborrheic keratopapilloma - keratopapilloma seborrhoica, seborrheic wart (verruca seborrhoica).
It occurs very often in dogs, especially in the second half of life. The favorite localization is areas exposed to trauma, but sometimes it also occurs in open areas. We observed multiple basal cell papilloma in a 2-year-old Shar Pei (slide 11) with long-term undiagnosed demodicosis, the cure for which, however, did not lead to spontaneous tumor reduction.
The initial forms of papilloma are flattened formations of yellow-brown skin, which during further growth can change color to dark brown, in accordance with the pigmentation of the animal. Clinically, flat and convex kerato-papillomas are distinguished. Flat forms occur singly or in groups in the form of round or oval formations with a diameter of 1-2 to 20-40 mm, sometimes they merge with each other.
Flat-shaped keratopapillomas are covered with vaguely defined papillae and fatty horny yellow-brown masses. The convex form of keratopapillomas often has a lobular structure, reminiscent of the appearance of a mulberry. Depending on the amount of horny mass located on the surface of clearly defined papillae or between them, convex keratopapillomas can have a soft or medium-density consistency.
Cytological examination reveals flat, uniform, non-keratinized cells of the basal layers of the epithelium, arranged in regular rows in the smear.
Histopathologically, keratopapillomas in dogs and cats, like the entire group of epithelial tumors, are characterized by the presence of papillomatosis, acanthosis and hyperkeratosis. The strands, intertwined with each other, are enclosed in loose connective tissue. It is believed that these tumors can also undergo malignancy - turn into malignant (skin cancer, carcinoma) tumors. The main difference between a malignant tumor and a benign one is the degree of cell atypia on one side. The more atypical the tumor cells, the less similar they are to the cells from whose tissue they are formed. On the other hand, the ability of a tumor to grow uncontrollably. For skin tumors, this is the ability to destroy surrounding tissues, penetrate the basement membrane (the layer on which the skin epithelium lies) and penetrate the vessels, giving metastases.
Carcinoma (ancient Greek ?????????? - “crab”, -??? from o????? - “tumor”), cancer is a type of malignant tumor developing from epithelial tissue cells of various organs (skin, mucous membranes and many internal organs). Cancer was first described in an Egyptian papyrus around 1600 BC. e. The papyrus talks about several forms of breast cancer and reports that there is no cure for the disease. The name “cancer” comes from the term “carcinoma” introduced by Hippocrates (460-370 BC), which denoted a malignant tumor with perifocal inflammation (Hippocrates called the tumor carcinoma because it looks like a crab). He described several types of cancer and also proposed the term oncos (Greek). Roman physician Aulus Cornelius Celsius in the 1st century. BC e. proposed to treat cancer at an early stage by removing the tumor, and at later stages - not to treat it at all. He translated the Greek word carcinos into Latin (cancer). Galen used the word oncos to describe all tumors, which gave the modern root to the word oncology.
That is, unlike papillomas, carcinomas are malignant tumors consisting of atypical cells with a change in structure, capable of destruction of surrounding tissues and metastasis (penetration into the blood and lymphatic vessels and spread throughout the body).
Basal cell carcinoma of the skin in dogs and cats (synonyms: basal cell carcinoma, basal cell epithelioma, basal cell carcinoma, cutaneous cancroid, cutaneous carcinoid), a tumor with limited and slow growth. It develops from the cells of the basal layer of the epidermis. Metastasizes rarely, but is prone to locally invasive and destructive growth. Types of basal cell carcinoma: ulcerating, pigmented, superficial, scleroderma-like (sclerosing), nodular. As a rule, dogs older than 5 years are affected, but the incidence in younger age groups of animals is increasing.
Risk factors for the occurrence of a tumor are exposure of the skin to inorganic arsenic compounds, industrial complex hydrocarbons, increased insolation (ultraviolet radiation), burns, injuries with scarring, and radiation. In non-pigmented animals, the disease occurs 4 times more often.
The disease begins with the appearance on the skin of a small, clearly demarcated nodule with a smooth pink or red surface.
Basalioma can be represented by satellite nodes or crusted, often ulcerated.
The tumor may contain varying amounts of melanin pigment, so its color varies, from pink to dark brown.
As the nodule grows, its central part ulcerates and becomes covered with crusts.
To make an accurate diagnosis, the doctor performs a scraping or biopsy, removing all or part of the tumor. This procedure involves scraping a small area of skin or making impressions from eroded surfaces. For histological examination, tumor excision is performed. The removed area is then examined under a microscope to see if it contains cancer cells.
Basalioma consists of cells resembling epithelial cells of the germinal layer of the epidermis.
These are, as a rule, cells with a large nucleus, several nucleoli, well-defined cytoplasm; cell size can vary from 5 to 30 microns.
As a rule, atypia is well expressed.
Treatment involves excision of the tumor with primary wound closure. Recovery occurs in 95% of cases. Allows you to examine a tissue sample with healthy edges. If necessary, plastic surgery is performed at the same stage.
Excision of regional lymph nodes is indicated only for clinical manifestations of their damage. Regional lymphadenopathy often accompanies ulcerated formations. Differential diagnosis with different processes is necessary (incl. tumor).
Canine cutaneous squamous cell carcinoma is a malignant epithelial tumor of the skin with squamous cell differentiation.
In dogs, this tumor is the most common tumor, while in humans, squamous cell carcinoma is the second most common tumor after basal cell carcinoma.
The main cause of tumors is the same as the previous tumor. Frequent exposure to the sun is one of the main reasons for its development, but it can also develop under the influence of other carcinogenic factors present in the environment. Most often, the areas of skin most exposed to sunlight are affected, and this type of cancer occurs three times more often in males than in females.
Squamous cell carcinoma develops more quickly than basal cell carcinoma; at first it spreads only locally at the place of its appearance, but subsequently it can spread to areas remote from the place of its initial occurrence.
Along with UV radiation, chemical carcinogens play an important role in the development of squamous cell skin cancer in dogs. This fact explains the frequent localization of the tumor on the limbs of dogs, since they are more often than other parts of the body exposed to urban pollution. Ionizing radiation, impaired antitumor immunity, and certain types of papillomavirus are also important factors in the occurrence of skin cancer in dogs and cats. Squamous cell skin cancer very often develops against the background of skin precancer, including genetically determined (xeroderma pigmentosum, albinism, etc.), or intraepidermal cancer (Bowen's disease).
The typical location of squamous cell carcinoma in cats is on the ears and dorsum of the nose. In appearance, the tumor initially resembles crusted lesions, then an ulcerative process develops. In dogs, tumors most often develop on the distal limbs, between the toes and on the ungual phalanges.
According to the clinical picture, tumoral and ulcerative types of squamous cell skin cancer are distinguished, which are often solitary and less often multiple. Tumor type characterized by a nodule or plaque of red-pink color or the color of unchanged skin, covered with crusts, horny masses or warty growths - this is the warty, hyperkeratotic variety. Over the course of several months, the tumor grows into the deep parts of the skin and subcutaneous fatty tissue, forming a dome-shaped node with a diameter of 2-3 cm or more, inactive, necrotic and ulcerating (slide 44-45). The papillomatous variety is characterized by more rapid growth, individual sponge-like elements on a broad base. Sometimes they have the shape of cauliflower or tomato, without the phenomena of hyperkeratosis (slide 42). The tumor is brown-red in color and may ulcerate at 3-4 months. Ulcerative type divided into superficial and deep. The superficial variety is characterized by an irregularly shaped superficial ulcer with clear edges, covered with a brownish crust. It spreads not in depth, but along the periphery. The deep variety is an ulcer with steep edges. The base of the ulcer is greasy, yellowish-red in color, the bottom is lumpy, with a yellow-white coating. Distributes along the periphery and into the underlying tissues. Metastases to regional lymph nodes in the ulcerative type of squamous cell skin cancer are observed, as a rule, 3-4 months after tumor formation. Lymph nodes enlarge, become dense (sometimes the consistency of cartilage), their mobility is limited (up to complete fixation) (slide 45).
The tumor on the fingers is characterized by invasive growth; when localized on the first phalanx, it quickly leads to the destruction of the bone of the first phalanx.
In the oral cavity, the tumor is as common as in the extremities, but it metastasizes more often.
Skin cancer is characterized by the presence of strands of cells in the stratum spinosum of the epidermis that proliferate into the dermis. Tumor masses contain normal and atypical elements (polymorphic and anaplastic). Atypia is manifested by cells of different size and shape, hyperplasia and hyperchromatosis of their nuclei, and the absence of intercellular bridges. There are many pathological mitoses.
The cytological picture is very characteristic. The preparation reveals a large number of large flat cells with abundant cytoplasm.
Some cells show signs of keratinization with loss of the nucleus, that is, they are highly differentiated. The degree of tumor differentiation is judged by the number of keratinized cells during cytology and areas of keratinization during histological examination.
Some cells are similar to basal cell carcinoma cells.
But in the preparation there are always cells more reminiscent of the surface cells of squamous epithelium, cells of different sizes and shapes with ugly nuclei and nucleoli, forming irregular layers and conglomerates.
There are keratinizing and non-keratinizing squamous cell carcinoma. Well-differentiated tumors demonstrate pronounced keratinization with the appearance of “horny pearls” and individual keratinized cells. Poorly differentiated tumors do not have pronounced signs of keratinization; they contain strands of sharply polymorphic epithelial cells, the boundaries of which are difficult to determine.
Many types of tumors are likely to develop in the perianal region of pets, such as lymphoma, squamous cell carcinoma, soft tissue sarcoma, melanoma, mastocytoma, melanoma and several others. But, in the vast majority of cases, tumors develop either from the hepatoid glands ( adenoma And adenocarcinoma of the hepatoid glands), or from the apocrine glands of the anal sacs ( adenocarcinoma of the apocrine glands of the anal sacs).
Hepatoid (perianal, circummanal) glands are located in the thickness of the skin around the anus, and are also scattered on hairless areas of the skin of the prepuce area, pelvic limbs and on the caudal surface of the root of the tail.. The name “hepatoid glands” comes from the fact that the morphological structure of these glands resembles the structure hepatocytes, and they are regarded as non-secreting sebaceous glands in adult dogs.
The apocrine glands of the anal sacs are located in the connective tissue surrounding the sacs, and secrete secretions into the cavity of the sacs. Anal sacs are paired blind skin diverticula located on the side of the anus.
In cats, unlike dogs, there are no analogues to the hepatoid glands of dogs, therefore adenoma and adenocarcinoma are not registered in them. The only type of tumor in cats is adenocarcinoma of the apocrine glands of the anal sacs, which is reported extremely rarely.
Table. Canine perianal tumors
|
Perianal glands |
Anal bags |
||
|
Benign |
Malignant |
Malignant |
|
|
Cell type |
Apocrine |
||
|
Tumor type |
Perianal adenoma |
Perianal adenocarcinoma |
Adenocarcinoma of the anal sacs |
|
Often in intact males, extremely rarely in females. |
Low incidence |
||
|
Hormonal factors |
Males: Usually in intact dogs, tesosterone dependent |
||
|
Localization and appearance |
Hairless areas of the perianal area; single, multiple, or diffuse: can be localized on the prepuce and head of the tail. |
Usually single; may be invasive; often ulcerated. |
Subcutaneous for 4 and 8 hours, hard and fixed; Primary tumors may be small with nodal metastases. |
|
Paraneoplastic syndrome |
No, (occasionally hypercalcemia). |
25%-50% - hypercalcemia. |
|
|
Metastasis pattern |
First - regional nodes, then to remote areas; the frequency of metastasis is up to 50%, especially with multiple local relapses. |
Usually to regional lymph nodes, then to distant sites. |
|
|
Special examination |
No; With cytology it is difficult to distinguish between benign and malignant formations. |
Abdominal imaging (radiography and/or ultrasound) focusing on the caudal abdomen; radiography of the chest cavity. |
Abdominal imaging (radiography and/or ultrasound): chest radiography; serum calcium levels and renal function indicators. |
|
Castration, conservative surgical removal** |
Wide excision of the primary tumor and removal of the lymph node (if involved); postoperative radiation for residual microscopic lesions: radiation or chemotherapy for unresectable lesions; There is little benefit from castration. |
Wide excision of the primary tumor and removal of the lymph node (if involved); postoperative radiation for the primary lesion and regional lymph nodes, as well as chemotherapy. |
|
|
Forecasts |
Excellent, less than 10% relapse rate after castration. |
Excellent or good (for tumors<5 см в диаметре); характерны рецидивы, но они могут формируются через несколько месяцев и могут быть повторно прооперированы. |
Excellent; good in some cases (depending on stage and treatment). |
* If multiple, recurrent, or large (as in males), consider testosterone secretion by the adrenal glands; Possible signs of Cushing's disease.
** Estrogens can cause tumor regression, but they carry the risk of bone marrow suppression. An adenoma may respond well to radiation, but surgical treatment is cheaper, faster and safer. The use of cryosurgery and electrochemotherapy is described.
Source. Withrow and MacEwen's Small Animal Clinical Oncology - 5th edition
Incidence and risk factors
Perianal adenoma is a benign tumor that develops from the circumnal (hepatoid) glands, accounting for 58%-96% of all perianal tumors in dogs; it is not registered in cats due to the absence of hepatoid glands. Tumor development is hormone-dependent; tumor growth is stimulated by androgens, while estrogens, on the contrary, inhibit it. The average age of development of the disease is 10 years, in the vast majority of cases it is observed in intact males, it is likely to develop in castrated females, due to the reduced level of estrogen in the body. Rarely, testosterone production by the adrenal glands can cause tumor growth. A breed predisposition is likely in Cocker Spaniels, Bulldogs and Samoyeds.
Perianal adenocarcinoma is a malignant tumor of the hepatoid glands, accounting for 3% to 21% of all perianal tumors. The average age of onset of the disease is 11 years. Unlike adenoma of the hepatoid glands, adenocarcinoma does not depend on the influence of androgens, and this type of tumor is recorded with equal frequency in both males and females. Giant breed dogs are more likely to be predisposed.
Adenocarcinoma of the apocrine glands of the anal sacs is an aggressive tumor originating from the above-mentioned glands. It accounts for about 17% of all neoplasms of the perianal area of dogs; few cases of adenocarcinoma have been described in cats (about 0.5% of all neoplasms of the skin and subcutaneous tissue). The average age of development of the disease in dogs is 9-11 years, in cats – 12 years. A probable breed predisposition is found in the English Cocker Spaniel and Siamese cats. The disease can appear at 5 years of age in dogs and 6 years of age in cats.
Pathology and behavior
Perianal adenoma is a benign tumor with appropriate behavior, characterized by slow growth, can reach significant sizes and ulcerate, but does not metastasize. Perianal adenocarcinoma metastasizes quite rarely; at the time of diagnosis, metastases are detected in 15% of cases. Presumably, metastases from adenocarcinoma form later, when the primary tumor becomes larger and more invasive. Adenocarcinoma most often metastasizes to regional sublumbar and pelvic lymph nodes; distant metastases are rare and can affect the lungs, kidneys, and bones. The histological distinction between these two tumors (adenoma and adenocarcinoma) is not always determined.
Adenocarcinoma of the apocrine glands is characterized by aggressive behavior and is significantly different from adenocarcinoma of the hepatoid glands, both clinically and histologically. At the time of diagnosis, metastases are formed in 46% of 96% of cases. The lesions are often unilateral, but in rare cases they can be bilateral. Typical sites for the development of metastases are regional lymph nodes (sublumbar and pelvic), while the size of the primary tumor can be less than 0.5-1 cm in diameter, while metastases in the lymph nodes can reach significant sizes. Distant metastases often form in the lungs, liver, spleen, bones, and less often in the heart, adrenal glands, pancreas, kidneys and mediastinum. An increase in calcium levels as a variant of paraneoplastic syndrome is observed in 27% of cases.
Due to the rare incidence of adenocarcinoma of the apocrine glands of the anal sacs in cats, the biology and behavior are not clearly defined.
Clinical signs
The medical history of hepatoid gland adenoma is characterized by slow growth (from months to years), single or multiple formations, hard, 5-3 cm in diameter. The typical location is around the anus, but can also develop on the root of the tail, prepuce, scrotum and groin area. Formations can become infected and ulcerate, but invasion into underlying tissues is not typical.
With perianal adenocarcinoma, the symptoms are similar to those of adenoma, but there is more rapid tumor growth as well as invasion into surrounding tissues and underlying structures. With significant sizes of primary mass formations or metastases of regional lymph nodes, a history of defecation disorders (constipation, pain, dyschezia) is likely.
Signs of adenocarcinoma of the anal sacs may be related to the primary tumor (perianal tenderness, swelling, bleeding, licking), obstruction of the pelvic canal by tumor metastases (tenesmus, constipation), or hypercalcemia (polydipsia/polyuria, anorexia, lethargy, vomiting). Also, a sign of dysfunction of the musculoskeletal system is likely, with the formation of metastases in the bones. In cats with adenocarcinoma of the anal sacs, the main signs are often associated with the primary tumor.
Diagnostics
The history of the disease and the characteristic appearance of adenoma and adenocarcinoma of the hepatoid glands allow us to make a presumptive diagnosis with a high degree of probability. Due to the fact that it is not always possible to distinguish between these types of tumors histologically, much attention is paid to the history of the disease, for example: the development of tumors in uncastrated male dogs is more typical for adenoma, and the development of tumors in a castrated male and non-sterilized females is more typical for adenocarcinoma. If adenocarcinoma is suspected, work is carried out to determine probable metastasis - rectal examination of the pelvic and sublumbar lymph nodes, visual examination (radiography ± ultrasound) of the thoracic and abdominal cavities. Cytological examination reveals typical hepatoid cells.
With adenocarcinoma of the apocrine glands of the anal sacs, the primary complaints may not be associated with perianal disease (eg polyuria/polydipsia due to hypercalcemia), examination of the animal requires a thorough rectal examination, visual examination of the abdominal and thoracic cavities, as well as a biochemical blood test. When identifying metastases in the lymph nodes and abdominal organs, ultrasound has some advantages over radiographic examination. CT and MRI can provide more complete data on the presence and nature of metastases. A presumptive diagnosis of high probability is made based on the detection of hard, discrete masses in the area of the anal sacs, together with suitable clinical signs. The final diagnosis is based on pathological and/or cytological examination of samples.
Adenocarcinoma of the anal sacs of cats is diagnosed similarly to those of dogs.
Differential diagnosis
Other benign and malignant formations of the perianal area (lymphoma, squamous cell carcinoma, soft tissue sarcoma, melanoma, transmissible venereal sarcoma, mastocytoma, melanoma, lipoma, fibroma, trichoepithelioma and some others).
Perianal fistula.
Perianal abscess.
Diseases of the anal sacs (with adenocarcinoma of the anal sacs).
Treatment
For adenoma of the hepatoid glands, it is the method of choice due to androgen dependence perianal adenoma, the vast majority of tumors regress. Surgical excision may be recommended in males with progressive growth and ulceration of the tumor, in case of recurrent tumors, as well as in females. In addition to conventional surgical excision methods, for localized lesions smaller than 2 cm, cryosurgery and laser ablation may be used. Radiation and hyperthermia are quite effective for adenoma of the hepatoid glands, but are rarely used due to the high cost and likelihood of various complications.
For adenocarcinoma of the hepatoid glands, aggressive surgical excision is used with adequate coverage of surrounding tissue. If the sphincter is involved, removing half or a little more of it leads only to temporary and passing problems with bowel movements. Due to the propensity of adenocarcinoma to recur locally, multiple palliative resections may be required over several years. After surgery, radiation or chemotherapy may be used, but the effectiveness of these methods has not been definitively determined. Surgical excision of lymph nodes can be used as palliative measures.
For adenocarcinoma of the apocrine glands of the anal sacs, the method of choice is aggressive surgical excision of the tumor together with a regional lymph node (if involved and resectable). Radiation and/or chemotherapy are used both postoperatively and as the only treatment, but the effectiveness of these methods is not clearly defined.
Forecasts
For hepatoid adenoma, most dogs respond well to castration ± local surgical excision.
For adenocarcinoma, prognosis largely depends on the stage of the disease; complete excision of small lesions can lead to complete recovery, but this type of tumor is prone to local recurrence and repeated excision of the formations is likely over several months or years.
With complete excision of adenocarcinoma of the anal sacs and the absence of metastases, the prognosis ranges from favorable to cautious. When metastases are identified, the long-term prognosis is unfavorable. Hypercalcemia resolves with complete removal of the tumor; recurrence of hyperalcemia is indicative of either tumor recurrence or the formation of metastases.
Photo1.12 year old male Labrador, mass near the anus, presumably perianal adenoma. Castration was chosen as the treatment method.
Photo 2. A 13-year-old mixed breed male, the owners went to the veterinary clinic about an ulcer below the anus; upon careful examination, several formations were discovered. Castration has been proposed as a treatment method.
Valery Shubin, veterinarian, Balakovo
Text of the article and photos from the book
SMALL ANIMAL DERMATOLOGY
A COLOR ATLAS AND THERAPEUTIC GUIDE
KEITH A. HNILICA, DVM, MS, DACVD, MBA 2011
Translation from English veterinarian Vasiliev AB
Peculiarities
Nodular sebaceous hyperplasia, sebaceous epithelioma, and sebaceous adenoma are benign tumors of the secretory cells of the sebaceous glands. They are common in older dogs, with the highest incidence in poodles, cocker spaniels, miniature schnauzers and terriers (sebaceous adenoma/hyperplasia) and in Shih Tzus, Lhasa Apso, Siberian Huskies and Irish Terriers (sebaceous epithelioma). Benign sebaceous gland tumors are uncommon in older cats, with a possible predisposition in Persian cats. Sebaceous adenocarcinomas are rare malignant tumors of older dogs and cats. Among dogs, cocker spaniels are predisposed.
Benign tumors of the sebaceous glands of dogs and cats are usually solitary, hard, raised, cauliflower-like or warty in appearance and vary from a few millimeters to several centimeters in diameter. The lesions may be yellowish or pigmented, lack hair, have a greasy appearance, or be ulcerated. Nodules with hyperplasia of the sebaceous glands can be multiple. Sebaceous adenocarcinomas tend to appear as solitary, hairless, ulcerated or erythematous intradermal nodules, less than 4 cm in diameter, that invade the subcutaneous tissue. Tumors of the sebaceous glands of dogs and cats occur most often on the trunk, paws, head and eyelids in dogs and on the head in cats.
Diagnosis
1 Distinct growth in the form of warts or cauliflower
2 Cytology:
Hyperplasia/adenoma of the sebaceous glands: The cells slough off in groups and look similar to normal sebaceous gland cells with foamy pale blue cytoplasm and small dark nucleoli.
Epithelioma of the sebaceous glands: small, uniform, sometimes melanotic epithelial cells with a small number of sebaceous gland cells.
Sebaceous gland carcinoma: extremely basophilic basophilic cell type with nuclear and cellular pleiomorphism.
3 Dermatohistopathology:
Hyperplasia of the sebaceous glands: multiple enlarged mature lobules of sebaceous glands with one peripheral layer of basaloid germ cells and a central duct. No mitotic figures are observed.
Sebaceous gland adenoma: Similar to hyperplasia, but with increased numbers of basaloid germ cells and immature sebaceous gland cells. Low mitotic activity and loss of organization are visualized around the central duct.
Epithelioma of the sebaceous glands: Multiple lobules of basaloid epithelial cells interspersed with reactive collagenous tissue and secondary inflammation. Early high mitotic activity is observed. Scattered areas of sebaceous gland cell differentiation, squamous metaplasia, or melanization may be observed.
Adenocarcinoma of the sebaceous glands: poorly defined lobules of large epithelial cells with varying degrees of differentiation and cytoplasmic vacuolization. The nucleoli are large and mitotic activity is moderately high.
Treatment and prognosis
1 For benign tumors of the sebaceous glands of dogs and cats, observation without treatment is advisable
2 Surgical removal (laser ablation or cryosurgery) of benign sebaceous tumors is usually indicated and sufficient for cosmetically unacceptable tumors or tumors
Which disturbs the animal.
4 The prognosis is good. Benign tumors of the sebaceous glands of dogs and cats do not invade locally, do not metastasize, and rarely recur after surgical removal. Sebaceous adenocarcinomas locally infiltrate surrounding tissues and sometimes involve regional lymph nodes, but distant metastasis is rare.
Photo 1 Tumors of the sebaceous glands of dogs and cats. This sebaceous adenoma on the nose exhibits a characteristic "cauliflower" appearance.
Photo 2 Tumors of the sebaceous glands of dogs and cats. This sebaceous gland adenoma persisted for several years with little progression.
Photo 3 Tumors of the sebaceous glands of dogs and cats. This adenoma of the sebaceous glands on the pinna demonstrates the characteristic size and shape of these tumors.
