Crystalline tissue deposits on a case of multiple myeloma

Crystalline tissue deposits were found at the time of autopsy in a 52-year-old male subject who had had multiple myeloma for 6 1/2 years and in whom the hyperviscosity syndrome had developed terminally. The tissue deposits were digested by trypsin, but could not be further characterized by immunohistochemical techniques. The crystals varied in size and shape and were located in tissue histiocytes, renal tubular cells, Leydig's cells, and adrenocortical cells. No crystals were identified within plasma cells. Their presence in the present case may have been related to the relatively long course of the disease, the high levels of serum proteins terminally, and unusual physicochemical structure of the secreted proteins, or possibly to the effects of chemotherapy.