Bronchogenic carcinoma with distant digital metastasis
Bronchogenic or squamous cell carcinomas of the lung in older cats can metastasize to the digits, resulting in the development
of destructive lesions. Affected cats are commonly asymptomatic for the primary neoplasia. Usually multiple digits are involved
on different feet. Diagnosis is based largely on radiography of the digits and thorax. Palliative treatment is recommended.
While rare, two paraneoplastic syndromes in cats can occur. An exfoliative dermatitis associated with thymomas occurs in middle-aged
to older cats. Lesions consist of large crusting and advance rapidly. Diagnosis is based on skin biopsy, thoracic radiography,
computed tomography and ultrasonography with fine-needle aspiration of the thymoma. Treatment involves mass removal (thymoma),
which generally results in resolution of clinical signs. However, the condition can recur.
Paraneoplastic alopecia in cats with pancreatic or bile-duct carcinomas occurs on the ventral abdomen and legs. The affected
skin appears smooth and shiny. These cats are often lethargic and anorectic. Biopsy of the affected skin reveals atrophy of
the follicles. Diagnosis can be difficult and is based on ultrasonography with biopsy; in some cases, exploratory laparotomy
is necessary to identify the tumor. Early diagnosis and treatment are critical to attempt tumor removal. However, by the time
advanced skin lesions are present, the prognosis is grave.
Lymphocytic mural folliculitis
This immune-mediated condition is unique to cats. It is characterized by alopecia of the legs and face and can be treated
Degenerative mucinotic mural folliculitis
This preneoplastic condition is more sinister than its cousin lymphocytic mural folliculitis, causing generalized hair loss
with thickened skin. It must be differentiated from T-cell lymphoma. Diagnosis is based on skin biopsy findings, and cats
should be tested for FIV infection. Unfortunately, these cases do not respond well to treatment.
Dr. Blake is a freelance technical editor and writer in Eudora, Kan.