Intranuclear inclusions in a dog with B-cell leukemia

A 7-year-old Shetland Sheepdog was presented with anorexia. A CBC indicated thrombocytopenia and neutropenia. Bone marrow cytology revealed that 67.7% of all nucleated cells (ANC) were anaplastic large mononuclear cells. These cells were confirmed to be of B-cell origin based on IgH rearrangement, immunohistochemical, and flow cytometric analysis. Microscopic examination revealed that the neoplastic cells had intranuclear inclusions resembling Dutcher bodies. Immunohistochemistry confirmed that the intranuclear inclusions were immunopositive for IgG antibodies. The periodic acid-Schiff reaction was negative for the presence of polysaccharides and related substances. Although the dog achieved complete remission with a multi-drug chemotherapy protocol, it ultimately died because of tumor progression and acute renal insufficiency on day 201. This is the first known case of canine acute B-cell leukemia with intranuclear inclusions resembling Dutcher bodies.