[An autopsy case of multiple myeloma accompanied by extensive nodular infiltration into the extraskeletal tissue]

Discussed is the case of a 41-year-old Japanese man dead at 4 months after start of his clinical course of multiple myeloma of the Bence-Jones protein lambda type of the skull. Autopsy findings revealed that atypical plasmacytes had infiltrated extensively into the testes, the retroperitoneum, including the pancreas and the renal pelvis, the bilateral pleura, the right subclavian soft tissue, and the meningism, but not to the liver, spleen, and lymph nodes. In both testes, which weighted 120 g and 100 g, respectively, myeloma cells were found disseminated throughout the testicular tissue. Such a testicular involvement in cases of a multiple myeloma is extremely rare. The pertinent literature also is reviewed.