A feline case of intestinal small T-cell lymphoma with prominent lymphoid follicle formation and concurrent intestinal large B-cell lymphoma.

An 11-year-old castrated male mixed-breed cat presented with a 2-week history of lethargy and anorexia. Abdominal ultrasonography revealed jejunal thickening and adjacent masses. As fine-needle aspiration cytology and PCR for antigen receptor gene rearrangement of the masses suggested small T-cell lymphoma, resection biopsy was performed. Based on histopathology and immunohistochemistry, a diagnosis of small T-cell lymphoma with prominent lymphoid follicle formation and concurrent large B-cell lymphoma was made. Postoperative chemotherapy with chlorambucil and prednisolone was performed. The cat survived for 728 days since initial presentation, with no recurrence of clinical signs or ultrasonographic abnormalities. To the best of our knowledge, this is the first report describing a feline case of intestinal small T-cell lymphoma with prominent lymphoid follicle formation and concurrent intestinal large B-cell lymphoma.