Extraskeletal Ewing's sarcoma with cutaneous involvement.

We report the case of a 13-year-old girl with extraskeletal Ewing's sarcoma involving the skin and subcutaneous tissue of the upper back. The patient underwent wide local excision and right axillary node dissection, and received chemotherapy with vincristine, actinomycin D, and cyclophosphamide. There was no evidence of recurrence or metastasis in eight months of follow up. Light and electron microscopic features were typical for this neoplasm. Tumor cells contained abundant glycogen, but failed to stain for desmin, keratin, neuron-specific enolase, or S-100 protein. We discuss the differential diagnosis of extraskeletal Ewing's sarcoma as well as theories of its histogenesis.