A 9-year old, F/S, domestic shorthair cat named Pudding presented to an internal medicine specialist for a history of anorexia of two weeks duration with vomiting of yellow bile every other day. On presentation, Pudding appears interested in food, but reluctant to chew and food falls from her mouth. CBC/chem/UA WNL. AUS reveals a hypoechoic mass at ileocecocolic junction with enlarged lymph nodes (3-4 cm). No additional abnormalities identified. FNA of abdominal mass, stained with Diff-Quick, was submitted.
Interpretation: Lymphoma of large granular lymphocytes.
Why do you need an FNA (versus biopsy) and 100x in this case? In large granular lymphocyte lymphoma, the characteristic azurophilic granules provide the final diagnosis. These can be very difficult to confirm at lower magnifications on cytology preparations and in biopsy sections (H&E staining), they stain very faintly, if at all.
Case follow up and additional information: This patient was discharged at the owner’s request and clinical follow up is not available, but in general this type of lymphoma in cats is of intestinal origin and has aggressive behavior. Granular lymphocytes can be further classified as T-cell or NK (natural killer) cell origin based on phenotyping, and are seen in low numbers in peripheral blood, but the majority are intestinal intraepithelial lymphocytes. In cats, unlike multicentric T-cell lymphoma, LGL lymphoma does not appear to be associated with retroviral (FeLV/FIV) status. LGL has also been well described in dogs and humans, having variable biologic behavior and clinicopathologic features, that are succinctly described in the reference provided below.
Reference: Roccabianca R, Vernau W, Caniatti M, Moore PF. Feline large granular lymphocyte (LGL) lymphoma with secondary leukemia: primary intestinal origin with predominance of a CD3/CD8(alpha)(alpha) phenotype. Vet Pathol. 2006 Jan;43(1):15-28. doi: 10.1354/vp.43-1-15.
Case Comparison: Hepatic LGL in a cat provided by the Armed Forces Institute of Pathology’s Joint Pathology Conference – note the Conference Comment. View Case and Biopsy Slide.