Multiple myeloma associated with IgA lambda gammopathy and multiple myeloma oncogene 1 in a Yorkshire terrier

Abstract

An eight-year-old spayed female Yorkshire terrier was presented with a one-month history of conspicuous weight-bearing lameness in the right hindlimb, mild anorexia, intermittent vomiting and marked polydipsia and polyuria. Radiographs revealed circular radiolucent foci of variable size in the skeleton. Haematological and serum biochemistry examination revealed mild leucopoenia with severe neutropaenia, mild non-regenerative anaemia, moderate thrombocytopoenia, moderate hyperglobulinaemia, mild hypoalbuminaemia, mild azotaemia and moderate hypercalcaemia. Quantification of serum immunoglobulins revealed elevated IgA and IgG. Serum protein electrophoresis showed a broad appearance with a β-region spike. Plasma cells accounted for 7.6% of the cells in the bone marrow. Serum immunofixation electrophoresis (IFE) revealed IgA lambda gammopathy. Immunohistochemistry in the bone marrow was diffusely positive for multiple myeloma oncogene 1 (MUM-1) and CD20. To our knowledge, this is first case report of multiple myeloma associated with IgA lambda gammopathy confirmed via IFE and immunohistochemical expression of MUM-1 in a dog.