Pathological Characterization of Lymphoma with Pulmonary Involvement in Cats

Studies evaluating histological patterns of lung infiltration by lymphoma in cats are lacking. We evaluated retrospectively the histological patterns of 125 necropsy cases of feline lymphoma collected over a 12-year period. Of the 125 cases, 16 showed lung infiltration (12.8%). Nine cats were female, seven cats were male and all were of mixed breed. Gross lesions observed in the lungs consisted of masses (25%) and nodules (18.7%); however, the majority of cases (56.2%) did not show any gross abnormality. Peribronchial-vascular infiltration (93.7%) was the most frequent pattern, followed by pleural (56.2%), interstitial (50%), nodular (37.5%) and alveolar (12.5%) patterns, but 75% of the cases had more than one pulmonary infiltration pattern. There were 14 (87.5%) B-cell and two (12.5%) T-cell lymphomas. Six cats (37.5%) were positive for feline leukaemia virus and three cats (18.7%) were positive for feline immunodeficiency virus. Diffuse large B-cell lymphoma was the most frequent type, accounting for 56% of all cases.