Extraskeletal Ewing's sarcoma of the nose.

A 20-year-old woman presented with nasal obstruction and slight epistaxis. The obstructing lesion was excised and microscopy showed a neoplasm composed of comparatively uniform undifferentiated cells forming solid nests. The cytoplasm of the cells was clear but poorly demarcated, partly vacuolated and contained much glycogen. Although widespread in the nasal mucosa, the cells did not penetrate into the underlying bone. The cells expressed the MIC2 gene (using the CD99 marker). Electron microscopy showed simple cells with a small number of mitochondria, many glycogen particles; there were no neurosecretory granules present. Early surgical treatment followed by chemo- and radiotherapy have greatly improved the prognosis of EWS: extraskeletal Ewing's sarcoma (EWS/PNET).