Patient characteristics, histopathological findings and outcome in 97 cats with extranodal subcutaneous lymphoma (2007-2011).

This study describes epidemiologic, clinical, macro- and microscopic tumour characteristics and outcome in 97 cats with subcutaneous lymphoma, an uncommon variant of feline extranodal lymphoma. Middle-aged (median 11 years), male (60.8%), Domestic Shorthair cats (89.7%) were commonly affected. Most tumours presented as a painless, firm, subcutaneous nodule or mass, with predilection to the lateral thoracic or abdominal wall, and the interscapular region. Deep subcutaneous invasion with extension into superficial or underlying tissues, extensive central areas of necrosis and peripheral inflammation were characteristic histopathological findings. Prevalence of retroviral infection was low. Local relapses after therapy were common (43.5%), and 32.2% had distant involvement later in course. Median overall survival was 148 days. Subcutaneous lymphoma should be considered a rare but important differential diagnosis for a subcutaneous mass in cats. Tumours show an aggressive biological behaviour. Treatment options including prognosis should be investigated in further studies.