Peripheral primitive neuroectodermal tumor involving the paravertebral and retroperitoneal regions.

A rare case of peripheral primitive neuroectodermal tumor (PNET) is reported. A 68-year-old woman complaining of lumbago was admitted to our hospital. Diagnosis was made based on pathological findings characterized by Homer Wright-type rosettes. Ultrastructural examination showed the presence of neurosecretory granules and short cytoplasmic processes, which were highly suggestive of neural differentiation. Chromosomal analysis of the neoplastic cells revealed translocation (11;22)(q24;q12), which is often found in Ewing's sarcoma and Askin tumor. These results strengthen the hypothesis of a common histogenesis for these small round cell tumors, and suggest common oncogenesis for these neoplasms.