Refractory thrombocytopenia with chromosome 11q23 abnormality.

Although cytopenia is a common manifestation of myelodysplastic syndrome (MDS), isolated thrombocytopenia is rare. The term "refractory thrombocytopenia" (RTC) has been proposed as a counterpart of refractory anemia. We describe here a case of RTC associated with chromosome abnormality on 11q23. A 59-year-old man was admitted because of severe thrombocytopenia. A bone marrow examination revealed an increased number of micromegakaryocytes and the absence of normal-sized megakaryocytes without obvious dysplasia in either the myeloid or the erythroid lineage. A remarkable increase of GPIIb/IIIa (CD41a)-positive precursor cells in the bone marrow was observed. Cytogenetic examination detected the chromosome abnormality, an addition on chromosome 11q23. Translocation of the HRX gene was not detectable by Southern blot analysis. The diagnostic problems of isolated thrombocytopenia and possible participation of gene(s) on chromosome 11q23 in megakaryocytopoiesis as well as early hematopoiesis are discussed.