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Hi all, just had the results back from a biopsy with a diagnoses of Bowen's disease. I was wondering if anyone has experience with this and could provide better info than what my vet provided - they really didn't know anything about it. My cat (she's 12) is prescribed Imiquimod 5% Cream (Aldara), she has two warty patches on her throat area, and lesions on her ears, and a wart on her lip. I wanted to ask if anyone might be able to suggest a pharmacy, or possibly an online pharmacy, in Canada where we could order it. We were quoted about $500 so we are hoping to find a better price for it! It is suggested she could take oral anti-inflammatory drugs and/or analgesics to be used for discomfort associated with the lesions. I am also wondering about diet, she has lost muscle mass and is somewhat 'gaunt' Her energy, mood, and appetite is good, although I can see she is tired inside sometimes. Thank you!

Here is some info the vet sent me via email:

Bowen disease affects cats older than age 10 years and is triggered by papillomavirus. This slowly progressive disease causes eroded crusted papules and plaques that are frequently found on the head and neck but can also appear on the shoulders and forelegs. This disease is not solar induced and does not metastasize.

Disease description:
Definition

Bowenoid carcinoma is an uncommon disease that is characterized by multifocal squamous cell carcinoma (SCC) in situ lesions in the skin. In situ refers to the histologic finding that lesions do not cross the epithelial basement membrane.1-3
Etiology and Pathophysiology
Bowenoid carcinoma has been fairly well described in humans and cats but only one case report has been published in the dog.4 Immunosuppression and papillomaviruses have been implicated as causative factors for in situ SCC, and DNA from multiple feline papillomaviruses has been isolated from a high percentage of feline BISC tissue samples.5-8,18-23 Bowenoid carcinoma has not been associated with feline leukemia or feline immunodeficiency virus infection.
Sun exposure and degree of pigmentation in the skin do not appear to play a role in the development of Bowen’s disease, which makes it clinically and histopathologically distinct from actinic (ultraviolet light-induced) SCC in situ. This latter condition more commonly develops as localized lesions on the face (especially nonhaired) of lightly pigmented or white areas on cats (See the Associate chapter on Feline Cutaneous Squamous Cell Carcinoma).1,8-11

Imiquimod 5% Cream (Aldara): This agent is an immune response modifier that is licensed to treat actinic keratosis, superficial basal cell carcinoma, and viral papillomas in humans. Imiquimod enhances both innate and cell-mediated immunity via the induction of cytokines. The cream is applied (after hair is clipped) in a thin film to lesions q 24-72 hours. Treatments are continued until resolution or stabilization of the lesion. A high response rate (including multiple complete responses) has been reported for cats with Bowenoid carcinoma.11 Treatment can be used long term and for any subsequent lesions that develop.11 Reported side effects include localized erythema, anorexia, and increased liver enzymes. Side effects are thought to result from patient ingestion (via licking) of the cream.

SUPPORTIVE THERAPY
An Elizabethan collar can be applied immediately after application of Aldara cream to prevent ingestion and systemic exposure. Oral anti-inflammatory drugs and/or analgesics can be used for discomfort associated with the lesions.
MONITORING and PROGNOSIS
Effective local therapy is often curative for individual in situ lesions; however, new lesions usually develop at other sites over time and require ongoing treatment. Untreated in situ lesions can progress to invasive SCC. Patients with Bowenoid lesions can also have invasive SCC concurrently; therefore, prompt treatment is recommended for all lesions documented or suspected to be in situ SCC. One case report exists of a cat with SCC in situ progressing to invasive SCC, with subsequent distant metastasis.7
  • Cause: Felis catus papillomavirus type 2.
  • While this papillomavirus commonly infects cats, Bowenoid in situ carcinomas are thought to be rare.
  • Viral plaques and Bowenoid in situ carcinomas probably represent a continuum depending on the presence or absence of dysplasia within the sample.
  • Signs: multiple, irregular, raised, keratinized or ulcerated up to 3 cm diameter skin lesions.
  • Disease usually in middle-aged to older cats.
  • Lesions can develop in pigmented or non-pigmented skin.
  • Diagnosis: histopathology possibly with immunohistochemistry or molecular diagnostics.
  • Treatment: surgical excision if necessary.
  • Cryotherapy may also be appropriate as lesion superficial.
  • Some evidence that imiquimod cream may be beneficial, although no controlled studies.
  • Prognosis: some lesions will remain stable for a long period of time without causing significant illness in the cat. However, up to 15% of Bowenoid in situ carcinomas may progress to squamous cell carcinoma. Bowenoidin situcarcinomas can also become extensive necessitating euthanasia due to repeated skin infections.
Pathogenesis
Etiology

  • Felis catus papillomavirus type 2.
  • This virus is detectible on the skin of a high proportion of cats.
  • Therefore, host factors are more important than the presence of the papillomavirus in determining which cats will develop disease.
 
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