Plasma cell leukemia with plasmablastic morphology in a dog

A 5-y-old female Golden Retriever was presented with a 2-wk history of hyporexia, vomiting, diarrhea, lethargy, weight loss, polyuria, and polydipsia. Clinical examination and ultrasonography revealed multiple organ enlargement with gallbladder and kidney nodules suggestive of disseminated neoplasia. Hematologic and biochemical analyses revealed pancytopenia, hypercalcemia, and monoclonal IgA gammopathy suspicious for a plasma cell neoplasm. Bone marrow and blood smear examination revealed neoplastic atypical cells highly suggestive of lymphoid origin. Autopsy confirmed the presence of homogeneous white masses and multifocal pale infiltrates in the spleen, kidney, small intestine, gallbladder, and urinary tract. Histologic features were consistent with a multicentric atypical plasma cell tumor. Tumor cells were negative for CD204, IBA-1, E-cadherin, CD3, CD5, CD79a, CD20, and PAX5, and positive for MUM1, consistent with plasma cell origin. The presence of > 20% of circulating blastic plasma cells was consistent with primary plasma cell leukemia with plasmablastic morphology, a disease rarely described in veterinary medicine.