Primary Erythrophagocytic Low-Grade Splenic T-Cell Lymphoma in a Cat: Clinical Case and Literature Review

Lymphoma is a common hematopoietic neoplasm in cats; yet hepatosplenic forms remain rare. This report describes a unique case of low-grade erythrophagocytic splenic T-cell lymphoma with suspected peripheral blood involvement in a six-year-old neutered male domestic shorthair cat. The patient presented with severe non-regenerative macrocytic normochromic anemia and moderate splenomegaly. Blood smears revealed mononucleated cells exhibiting erythrophagocytosis. Splenic cytology and flow cytometry were consistent with a reactive process, leading to a presumptive diagnosis of immune-mediated anemia. The condition proved refractory to immunosuppressive therapy with prednisolone and cyclosporine. After splenectomy, histopathology showed diffuse erythrophagocytosis and white pulp hyperplasia. Definitive diagnosis was achieved only by PARR analysis, which demonstrated a monoclonal T-cell receptor gene rearrangement within a polyclonal background. This confirmed a neoplastic T-cell population despite the mature morphology of the lymphocytes. Treatment with chlorambucil and prednisolone resulted in progressive resolution of the anemia. The cat remains alive 13 months after splenectomy. This case highlights the diagnostic challenges of low-grade lymphomas, in which reactive features can mask neoplasia, and underscores the critical role of PARR analysis in differentiating monoclonal T-cell proliferation from complex reactive processes in feline splenic disorders.