Rhabdomyosarcoma (RMS) masquerading as acute leukemia (AL) is very rare. We describe three cases with RMS without any symptoms of solid tumors. Bone marrow (BM) showed approximately 95% of blast-like abnormal cells, lacking almost all of the surface antigens of myeloid- and lymphoid-lineage. The immunohistochemistry revealed positive of the cells for actin, desmin and myoglobin. It is important to examine BM samples by immunohistochemistry, when a flow cytometric analysis reveals an unusual presentation.
(c) 2008 Wiley-Liss, Inc.