A follow-up study of bone marrow chromosomes and in vitro colony growth in patients with mastocytosis.

Proliferation of mast cells can give rise to many clinical manifestations in patients, and an association with hematological disorders has been pointed out. The study was initiated to determine whether patients with mastocytosis show a clinical progression in relation to bone marrow cell parameters analyzed. During a median follow-up period of 5.5 years, 10 patients with mastocytosis were re-examined with regard to clinical symptoms, urine histamine metabolites (U-MeImAA), bone marrow cells examined with chromosome analyses, and in vitro stem cell growth for CFU-GM. Seven patients showed a clinical progression with increase of either symptoms, bone marrow infiltrates of mast cells or U-MeImAA. One patient with a myeloproliferative bone marrow morphology had a malignant course. Four of the 7 patients showed an increased colony growth, while 3 showed a decreased growth, in the second examination compared with the first examination. One patient had a persistent clone with the chromosome aberration 9p+. A variable pattern was observed in the other patients, in resemblance with findings in chronic myeloproliferative disorders. Our conclusion is that mastocytosis belongs to the myeloproliferative disorders.