1995 Volume 48 Issue 11 Pages 852-855
A case of multiple myeloma was found in a six-year-old female Gechingen miniature pig. A few atypical plasma cells were present in the peripheral blood, but the animal did not have elevated γ-globulin in serum. At necropsy the spleen was highly enlarged with multiple nodules. Each of the sternum and two ribs had a neoplastic nodule on its surface. Histologically, there were neoplastic cells in the bone marrow, spleen, liver, kidneys and pancreas, and bone destruction by neoplastic proliferation was detected in the cortex of the ribs. The neoplastic cells were of moderate size, oval to round in shape, and had an eccentrically placed nucleus with chromatin clumps. The cytoplasm was weakly basophilic in haematoxylin and eosin preparations and pyroninophilic, and frequent cells contained PAS positive bodies. There was intracytoplasmic IgM in many neoplastic cells, and dilated cisternae of rough endoplasmic reticulum were the most predominant ultrastructural feature of the neoplastic cells. This tumour was a nonsecretory IgM myeloma, which was very rare in domestic animals.