A CASE OF BONE-MARROW MASTOCYTOSIS ASSOCIATED WITH MULTIPLE-MYELOMA

Mastocytosis is a term used for a spectrum of disorders characterized by abnormal growth and accumulation of mast cells. The cutaneous varia nts of the disease have to be distinguished from systemic mastocytosis (SM), in which at least one extracutaneous organ is involved. In cont rast to cutaneous mastocytosis, SM is often associated with another he matologic neoplasm. In most cases clonal myeloid malignancies such as a myeloproliferative or myelodysplastic syndrome occur. In a few cases of SM, however, clonal lymphoid disorders have been described. We her e report on a case of SM associated with multiple myeloma, At first pr esentation, the 48-year old female patient showed monoclonal IgG lambd a gammopathy and bone marrow (BM) mastocytosis, but no BM plasma cell infiltrates. Eight years later, the patient presented with BM mastocyt osis and overt multiple myeloma. The co-existence of myeloma and masto cytosis was demonstrable by staining serial BM sections with antibodie s against mast cell tryptase, CD68R, and the plasma cell marker VS38c. Interphase FISH analysis of BM sections revealed a numeric gain of ch romosome 5 and chromosome 7 in the plasma cells but not in the mast ce ll infiltrates, thereby confirming the presence of two different neopl astic cell populations. To our knowledge, this is the first report des cribing the co-existence of multiple myeloma and mastocytosis.