Evidence for the clonal origin of acquired hypomegakaryocytic thrombocytopenic purpura from a sex chromosome mosaic

Cytogenetic studies performed on a 79-year-old female presenting with clinical and hematologic features of acquired hypomegakaryocytic thrombocytopenic purpura revealed sex chromosome mosaicism in blood lymphocytes (45,X/46,XX/47,XXX). The presence of only 45,X cells in the bone marrow is consistent with a unicellular origin of acquired hypomegakaryocytic thrombocytopenia in this patient. These studies also suggest that, in some instances, this disorder may originate at the level of the pluripotent hematopoietic stem cell.