[Ectopic production of amylase by a non-producing type of multiple myeloma].

The patient was a 64-year-old woman who was admitted to our hospital because of lumbago. A diagnosis of multiple myeloma (non-producing type) was made, based on (1) the presence of multiple osteolytic lesions, (2) hypercellular marrow with 64.2% plasmacytoid malignant cells, (3) no monoclonal gamma-globulin was detected in the serum and urine, and (4) abnormal monoclonal gamma-globulin was also not detected in the cytoplasm and membranes of these malignant cells. After several courses of chemotherapy, a pleural effusion infiltrated by myeloma cells developed and the patient's serum contained a markedly increased amylase activity of salivary-type. Amylase activity was also detected in vitro in the supernatant of cultured myeloma cells established from the patient's pleural effusion. The presence of alpha-amylase in the myeloma cells, which were derived from pleural effusion, was demonstrated immuno-histochemically. These observations indicates that amylase was ectopically produced by these myeloma cells. Interestingly, 14 out of 20 metaphases in the cells derived from pleural effusion showed translocation of 1p22 near the region of 1p21, where the amylase gene was assigned.