Ultrastructural, immunohistochemical, and cytogenetic study of a malignant peripheral neuroectodermal tumor in a patient seropositive for human immunodeficiency virus.

A case of malignant peripheral neuroectodermal tumor occurring during the course of a human immunodeficiency virus (HIV) infection is reported. The patient was a male homosexual who presented with a rapidly enlarging tumor of the posterior lower thoracic wall. By light microscopic examination the tumor was a small cell tumor showing occasional structures suggestive of Homer-Wright rosettes. The strong positivity for neuron-specific enolase and the neurosecretory granules indicated the neural differentiation of the tumor. Its precise nature was shown cytogenetically by the presence of the t(11;22) translocation, which distinguished it from the classical neuroblastoma.