[Amylase-producing plasma cell dyscrasia. Genomic analysis in a case of intramuscular tumor formation and a review of the literature].

We describe a 53-year-old male patient with multiple myeloma (IgA, kappa) who showed massive intramuscular tumors and hyperamylasemia of the salivary (S) type 10 months after initial diagnosis. Suspension culture of the abnormal plasma cells in the pleural fluid showed the production of S-amylase, which was confirmed by the expression of S-amylase mRNA comigrating with salivary gland mRNA. Cytogenetic analysis of the cells showed common abnormalities 1p+q-and 8q+. They expressed IL-6 mRNA, but not c-myc mRNA. Neither structural abnormality nor amplification was detected in the alleles of S amylase, and c-myc using Southern blot analysis. All of the eight patients with plasma cell dyscrasia with hyperamylasemia reported so far (including the present one) are Japanese, and showed S-type hyperamylasemia and extramedullary tumor formation at initial diagnosis or during the course of the disease. All of the four patients in whom cytogenetic analysis was performed had structural abnormalities of chromosome 1, on which the S-amylase gene is known to be located, although the break point were variable.