[An autopsy case of plasmacytoma of the thyroid gland]

An autopsy case of a 75-year-old woman with plasmacytoma of the thyroid gland is presented. There were no toxic symptoms and no abnormal serum protein. On autopsy, a nodule measuring 5.5 X 4.5 X 8 cm was found in the left lobe of the thyroid gland. No myeloma lesions were found in the bone marrow or in other organs. Histologically, the marginal area of the nodule was occupied by typical plasmacytoma, whereas necrotic tissues resembling anaplastic carcinoma were present in the central portion. Chronic thyroiditis was not associated. Immunohistochemically, only the kappa-light chain was demonstrated in the cytoplasm of the tumor cells.