Hyperviscosity syndrome with IgM monoclonal gammopathy and hepatic plasmacytoid lymphosarcoma in a cat

Abstract

A 19‐month‐old cat investigated because of depression, anorexia, polyuria, and polydipsia was found to have hepatomegaly, retinal haemorrhages, and distended tortuous retinal veins. Prolonged bleeding occurred after venipuncture, and serum was hyperviscous due to an immunoglobulin M monoclonal gammopathy. Prothrombin and activated partial thromboplastin times were prolonged, thrombin clotting time was only slightly prolonged and the activities of coagulation factors VII, VIII and IX were normal. The cat died suddenly before the origin of the immunoglobulin could be determined. Hepatic plasmacytoid lymphosarcoma was found at post‐mortem examination. The pathophysiology of hyperviscosity syndrome is discussed and the observations in this cat are compared with those reported in the dog.

Histopathologic, Immunohistochemical, and Cytologic Analysis of Feline Myeloma-Related Disorders: Further Evidence for Primary Extramedullary Development in the Cat

“…16,17,21,45,46,77 (6) Only 32% of feline MRD specimens were CD79a + in this series. CD79a is expressed from early B-cell progenitors onwards and is variably expressed by human myeloma cells.…”

“…33 Since then, a diverse array of sometimes confusing terminology and diagnostic criteria have been used for feline MRD, including multiple myeloma, lymphoma, plasmacytoid lymphosarcoma, plasma cell dyscrasia, plasmacytoma, plasma cell sarcoma, and plasma cell tumor. 18,20,30,51,52,62,77 In a previous report, 49 we classified reported feline MRD in the following diagnostic categories: 1) myeloma (intramedullary or combined intra-and extramedullary involvement), 49 2) cutaneous extramedullary plasmacytoma (CEMP), 49 3) noncutaneous extramedullary plasmacytoma (NCEMP), 49 4) solitary plasmacytoma of bone (SPB), 50 5) IgM (Waldenströ m's) macroglobulinemia, 45,77 6) immunoglobulin secreting lymphoma (IgSL), 17 and 7) myeloma cell leukemia. 19,54,59 Few publications describe the cytologic or histologic features of feline MRD.…”

“…32,39,59 Many histopathologic reports of feline MRD simply describe myeloma cells as plasma cells. However, other terminology has been used: ''plasmacytoid cells'' have been reported in single cases of plasmacytoma, 9,24,43 and ''lympho-plasmacytoid'' appearance was described in 2 cases reported as lymphoma (IgSL) 62,77 and 1 case reported as multiple myeloma. 20 Small to medium-sized lymphocytes were described in 1 case of IgSL.…”

Multiple myeloma with central nervous system involvement in a cat

“…Although results in that study revealed that affected cats most commonly had paraproteinemia and bone marrow plasmacytosis, the authors suggested that bone marrow aspirates and serum protein concentrations should be sufficient for diagnosing multiple myeloma and that diagnostic criteria should also include visceral organ infiltration and atypical plasma cell morphology. 3,4,6,7 The cat of our report met the historical criteria for a diagnosis of multiple myeloma as extrapolated from humans. 5 Bone marrow involvement is used to distinguish between the 2 neoplasms.…”

“…[1][2][3] Radiation therapy was discussed with the owners and declined. [1][2][3] Radiation therapy was discussed with the owners and declined.…”