Nasal embryonal rhabdomyosarcoma with bone marrow metastasis simulating acute leukemia: A case report and review of the literature.

We present a case of a nasal rhabdomyosarcoma (RMS) in a 27-year-old male with epistaxis and nasal obstruction due to a mass, which was subjected to prophylactic tumor embolization. However, histopathological study on the nasal biopsy was impossible due to necrotic changes. As blast cells were present in peripheral blood samples, a bone marrow biopsy was recommended in order to reach a definitive diagnosis. The possibility of an RMS in cases of bone marrow infiltration by a diffuse tumor constituted by small, round, blast-like cells mimicking acute leukemia should be assessed. Immunohistochemical staining in bone marrow biopsy and flow cytometry in aspirate samples may help to establish the diagnosis (CD45 negativity and CD56 positivity) and cytogenetic studies can be useful in identifying a RMS subtype. When clinically possible, it is desirable to await the results of the tumor immunophenotype and those of the primary mass or bone marrow biopsy to avoid possible errors of diagnosis and treatment.