[Specific cytoplasmic crystalline inclusions in multiple myeloma with amyloidosis]

It is widely known that multiple myeloma is sometimes followed by amyloidosis. It is also not particularly rare that inclusions exist in myeloma cells. However, there has been no previous report of a case of myeloma with both inclusions and amyloidosis. A 60-year-old female initially complained of a tendency to bleed, which was caused by fibrinolysis. Amyloid deposition in bone marrow stroma and the gastric submucosa was recognized, in addition to crystalline inclusion in the cytoplasm of myeloma cells. An immunoelectron microscopic study demonstrated the amyloid fibrils and the crystals to react positively to anti-lambda serum. No crystals were found in macrophages, and no relationship was recognized between lysosomes and crystalline inclusions in the cytoplasm of myeloma cells. This case had disturbed transportation or secretion of the lambda type L chain and it was considered that crystals derived from the lambda type L chain were formed in the cytoplasm of myeloma cells.