Understanding Canine Epitheliotropic Lymphoma in Dogs

Canine epitheliotropic lymphoma is a type of cancer that affects the skin and mucous membranes of dogs. It's a serious condition that requires prompt attention from a veterinarian.

This type of lymphoma is often associated with the presence of a specific virus, the Epstein-Barr virus. The virus can cause changes in the DNA of skin cells, leading to the development of cancer.

The symptoms of canine epitheliotropic lymphoma can vary depending on the location and severity of the disease. Common signs include skin lesions, ulcers, and bleeding.

Dogs with this condition often experience a significant decline in their quality of life due to the chronic pain and discomfort caused by the disease.

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Canine epitheliotropic lymphoma presents in a highly variable way, often making it difficult to diagnose. This type of neoplasia is sometimes referred to as "the great mimicker" due to its tendency to masquerade as other conditions.

Some breeds, such as English cocker spaniels and boxers, may be predisposed to this type of lymphoma. The average age of onset is between 9 to 12 years.

Dogs with epitheliotropic lymphoma often experience intense pruritus, but not always - in one study, only 40% of dogs showed signs of pruritus.

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Dogs with mycosis fungoides can have a highly variable clinical presentation, earning it the nickname "the great mimicker." This means that it's often misdiagnosed.

The average age of onset is 9 to 12 years, with some studies noting that English cocker spaniels and boxers may be predisposed to this type of lymphoma.

Most dogs with mycosis fungoides are intensely pruritic, but interestingly, a study found that only 40% of dogs in one retrospective study were observed to be pruritic.

Mycosis fungoides has four main clinical presentations: pruritic erythema and scaling, mucocutaneous erythema, infiltration, depigmentation and ulceration, solitary or multiple plaques or nodules, and infiltrative and ulcerative oral mucosal disease.

In a study by Fontaine et al, diffuse erythema was noted in 86.6% of cases, scaling in 60%, and focal hypopigmentation in 50% of cases.

Footpads may also be affected, with some dogs experiencing hyperkeratosis, depigmentation, or ulceration.

Systemic signs of illness and lymphadenopathy may be present along with cutaneous signs, and mucocutaneous involvement occurs in up to 50% of patients.

Breed/Species predisposition plays a significant role in the clinical presentation of certain conditions.

Some breeds, like English Cocker Spaniels, appear to be overrepresented in cases of this condition.

Diagnosis can be a bit of a challenge, but it's crucial to get it right.

Cytology samples from lesional skin may reveal round cells that suggest a hemolymphopoietic tumor.

These round cells might not be atypical, making it hard to differentiate them from clonal expansion.

A definitive diagnosis requires a skin biopsy submitted for histopathology.

Inflammation in samples is characterized by infiltration of neoplastic T-lymphocytes with a tropism for the epidermal or mucosal epithelium.

Neoplastic lymphocytes often target adnexal structures, especially the follicular wall.

Pautriers microabscesses, which are intraepithelial neoplastic lymphocytes, may be noted in specimens.

In samples where these lymphocytes are diffuse within the epidermis, they often remain within the lower levels.

Infiltration of apocrine sweat glands by neoplastic lymphocytes occurs in up to 70% of cases and is considered diagnostic for CTCL.

The epidermis may be moderately acantholytic, but hyperplasia is not prominent in the disease.

Masitinib has been shown to be effective in treating canine epitheliotropic lymphoma, with complete remission occurring in 2 of 10 dogs.

The study found that side effects occurred in six dogs, and were mostly mild to moderate.

Masitinib's effects are likely not generated through the KIT receptor, as the KIT receptor was negative in all eight dogs tested.

Immunohistochemistry was available for eight dogs, and six of them stained strongly positive for stem cell factor (SCF).

Platelet-derived growth factor (PDGF)-AA was weakly positive in two and negative in six dogs, while PDGF-BB was negative in four tumours, weakly positive in one, and strongly positive in three.

Five dogs showed strong expression of PDGFR-β, two showed weak expression, and one was negative.

Canine lymphoma is a relatively common and important disease seen by veterinarians, but there's a lack of comprehensive reviews of the literature regarding remission and survival times following chemotherapy.