Multiple Myeloma in a Dog

History: 12 -year -old dog, Labrador retriever, spayed female, showing weight loss and bilateral detached retina. Chemistry panel revealed hypergammaglobulinemia.

Cytological description: The images from the bone marrow smears show a high cellularity of bone marrow cells. Several megakaryocytic and numerous erythroid and myeloid precursors are present. These are of normal morphology and show a complete maturation process. There is severe infiltration by well-differentiated plasma cells with a lower cellularity of small and medium-sized lymphocytes.

Comments: Multiple myeloma is a neoplastic proliferation of plasma cells primarily involving the bone marrow. For a confirmatory diagnosis of multiple myeloma, 3 out of 4 of the following findings should be present: multiple osteolytic lesions on radiographic examination, severe hyperglobulinemia, proteinuria (Bence-Jones proteinuria), and hypercalcemia. Multiple myeloma may also infiltrate other internal organs such as the liver and spleen. Retinal detachment may be a consequence of hyperviscosity resulting from the hyperglobulinemia.

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