An autopsy case of extraskeletal Ewing's sarcoma followed up for 24 years.

A long-term (24 years) follow-up case of extraskeletal Ewing's sarcoma is reported. The light microscopic examination showed features hardly indistinguishable from Ewing's sarcoma of the bone, that is, the tumor cells were diffusely arranged and uniform in size and shape, and possessed glycogen in the cytoplasm. Homer-Wright rosettes were found only in the autopsy material. An immunohistochemical study using a neural marker (neuron-specific enolase) demonstrated positive staining in most tumor cells. An ultrastructural study revealed intracytoplasmic glycogen particles and incomplete neural characters as follows: the cytoplasmic processes resembled neural processes without neurosecretory granules, microtubules or neurofilaments. These findings suggest that this case finally acquired an incomplete neural character with repeated recurrence. This tumor was diagnosed extraskeletal Ewing's sarcoma, but in future it may be categorized as primitive neuroectodermal tumor (PNET).