Presumptive histiocytic neoplasm with unusual immunophenotype in a cat

Abstract

True histiocytic proliferative diseases have been infrequently documented in the cat, with progressive histiocytosis and histiocytic sarcoma representing the bulk of the reported cases. A 5-year-old, neutered male domestic shorthair cat presented with a 1-month history of anorexia, depression, mucosal pallor and persistent non regenerative anemia. On admission, the cat appeared depressed, icteric, dyspneic and had moderate splenomegaly. The cat had a severe, temporarily regenerative anemia, and a blood smear evaluation revealed numerous neutrophil-and monocytephagocytosed erythrocytes. Splenic and bone marrow aspirate smears were predominated by a monomorphic population of individual or aggregated round-to-oval cells, likely of histiocytic origin that often phagocytosed erythrocytes and leukocytes. A comprehensive immunocytochemical staining panel failed to definitively identify the neoplastic cells. This report emphasizes the clinical course, the sequential hematological abnormalities, the cytology and the unusual immunophenotype of a presumptive histiocytic sarcoma in a cat.

Practical bone marrow cytology in the dog and cat

“…Phagocytosis of blood cells and their precursors is rare in the BM of healthy animals and generally involves only mature erythrocytes (Harvey, 2012b). Frequent BM erythrophagocytoses may occur in immune-mediated hemolytic anemias, in erythrocytic parasites (e.g., Babesia sp., hemoplasmosis), hematopoietic neoplasms, after blood transfusion, and in histiocytic neoplasia, including the hemophagocytic histiocytosis (Mylonakis et al, 2012), while idiopathic cases have also been reported (Weiss, 2007).…”

“…These features were also demonstrated in spleen aspirates (not shown) (Giemsa, x400). [From:Mylonakis ME et al, (2012) Presumptive histiocytic neoplasm with unusual immunophenotype in a cat. Comp Clin Pathol, 21: 231-236].…”