Plasma cell leukemia with plasmablastic morphology in a dog

Abstract

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.

Case report: Suspected plasmablastic lymphoma in a dog resembling the clinical presentation in humans

“…Neoplastic cells were positive for CD79a, MUM-1/IRF-4, LLC (lambda light chain), and CD18 but negative for CD3 ( 17 ). A 5-year-old Golden Retriever was diagnosed with plasmablastic leukemia by positive immunolabeling for MUM-1/IRF-4 but negative for CD204, Iba-1, E-cadherin, CD3, CD5, CD79a, CD20, and PAX5 ( 18 ). In one dog with non-epitheliothropic plasmacytic lymphoma, the tumor cells presented positive immunoreactivity for CD79a and MUM-1/IRF-4 but negative immunoreactivity for CD20, PAX5, CD3, and Iba1 ( 12 ).…”

“…A 9-year-old mixed breed dog was diagnosed with Mott lymphoma in the liver and the spleen and treated with CHOP chemotherapy and, after relapse, with lomustine and L-asparaginase, resulting in a survival of 5 months ( 15 ). A dog diagnosed with plasma-cell leukemia with plasmablastic morphology was treated with a combination of melphalan and prednisolone, but the disease progressed and the dog was euthanized after 15 days ( 18 ).…”

“…In a more recent retrospective study of 203 canine multicentric lymphomas, lymphomas with plasmacytic or Mott cell differentiation corresponded to approximately 2% of all the cases, but again no PBL cases were reported ( 11 ). In the literature, there are also occasional case reports of lymphoma with plasmacytic or Mott cell differentiation with the involvement of skin ( 12 ), gastrointestinal tract and abdominal lymph nodes ( 13 , 14 ), liver and spleen ( 15 ), and multicentric lymphomas ( 16 , 17 ), including a case report with confirmed leukemia with plasmablastic differentiation ( 18 ). To the best of the authors' knowledge, previous cases of PBL with presentations similar to human PBL have never been reported.…”

“…This can be due to underreporting and lack of awareness of the presence of this specific type of lymphoma or difficulty in achieving a final diagnosis. The diagnosis of plasmacytic lymphoma is based on the plasmacytoid and/or Mott cell differentiation morphology and is confirmed by positive immunoreactivity for CD20, CD79a, and/or MUM-1 ( 15 , 17 , 18 ). However, a definitive diagnosis of PBL in dogs is difficult due to the lack of typical histological appearance and specific immunohistochemistry stains that are available for human PBL.…”

Bite-size introduction to canine hematologic malignancies

“…Unlike in humans, cytogenetic abnormalities in canine plasma cell disease have not been well characterized. Waldenström's macroglobulinemia, monoclonal gammopathy of unknown significance (MGUS), solitary osseous plasmacytoma (SOP), extramedullary plasmacytoma (EMP) and plasma cell leukemia have all been described in dogs but apart from MM and EMP these diseases are rarely encountered [74][75][76][77][78][79][80] . Older dogs aged 8-10 years are typically affected by MM and EMP, with no clear breed predispositions for MM, however cocker spaniels, West Highland white terriers, Yorkshire terriers, Airedale terriers, boxers and golden retrievers are over-represented when EMP is diagnosed 79,79 .…”