Trisomy 21 in bone marrow cells of a patient with a prolonged preleukemic phase.

The clinical, hematologic, and cytogenetic findings are described in a patient who developed clinical and hematologic features of acute myelogenous leukemia (AML) after a three-year period of observation with unexplained thrombocytopenia. Five months before the diagnosis of AML she developed hepatosplenomegaly and a lupus-like syndrome. At this time she was also found to have trisomy 21 in all bone marrow cells studied, in addition to trisomy 8 in a few cells. The finding of trisomy 21 in all of the bone marrow cells examined could reflect a nonrandom alteration in the leukemic stem line or it might indicate that mosaic patients with trisomy 21 cells in their bone marrow share the increased risk of AML that has been documented for trisomy 21 patients.