METASTATIC EXTRAMEDULLARY PLASMACYTOMA OF THE COLON AND RECTUM IN A DOG

Stage-3 extramedullary plasmacytoma of the large intestine was diagnos ed in an 8-year-old Labrador Retriever. Three primary tumors were loca ted in the colon and rectum, with metastasis to local lymph nodes and the spleen. The disease was associated with a monoclonal serum protein spike identified as IgG. Treatment consisted of surgical excision fol lowed by chemotherapy, using melphalan and prednisone. The dog remaine d free from clinical signs of disease and adverse effects of the chemo therapy at 9 months. Findings in this dog indicated that extramedullar y plasmacytoma may be an aggressive disease, associated with spread to distant sites and monoclonal gammopathy.