Refractory thrombocytopenia, an unusual myelodysplastic syndrome with an initial presentation mimicking idiopathic thrombocytopenic purpura.

Refractory thrombocytopenia (RTC) is an unusual subtype of myelodysplastic syndrome (MDS) that initially presents as chronic pure thrombocytopenia. Because of the lack of distinguishable dysplasia, RTC has often been misdiagnosed as idiopathic thrombocytopenic purpura. We describe the case of a patient with RTC and trisomy 8 for whom a bone marrow mononuclear cell (BMNC) gene expression profile was obtained by means of a complementary DNA microarray analysis. Compared with the healthy control subject, the RTC patient differentially expressed 105 genes, of which 88 were down-regulated and 17 were up-regulated. The expression pattern of 16 genes, including those for RNA helicase-related protein (RNAHP), heat shock 105kD (HSP105B), interferon-related developmental regulator 1 (IFRD1), cyclin C (CCNC), and DNA-damage-inducible transcript 3 (DDIT3), which are usually seen in BMNCs from typical MDS patients, was observed in this case. However, this RTC patient exhibited an expression pattern distinct from that of other MDS patients. We suggest that RTC be classified as a subtype of MDS on the basis of its characteristic clinical-hematologic features and specific molecular basis.