[Amylase-producing multiple myeloma: a case report].

A 80-year-old man was admitted because of acute-onset thrombocytopenia and renal failure. He was diagnosed with Bence Jones (lambda) -type multiple myeloma associated with sepsis with methicillin-resistant Staphylococcus aureus. On admission, serum amylase activity was elevated to 1,814 IU/l (98% salivary type; S-amylase). Several days after admission, he developed bilateral myelomatous pleuritis. The activity of S-amylase in the effusion was 5,495 IU/l. Myeloma cells in the pleural effusion were positive for cytoplasmic amylase with an antibody against human amylase. High S-amylase activity was detected in the supernatant of cultured myeloma cells in the effusion. Furthermore, S-amylase gene expression was detected by RT-PCR. A diagnosis of amylase-producing multiple myeloma was made. The patient died of renal insufficiency complicated by severe DIC. We report a rare case of amylase-producing myeloma confirmed by immunocytochemistry, culture method, and gene expression.