[Malignant paraganglioma of the peri-iliac artery].

A malignant nonfunctioning paraganglioma of the pelvic retroperitoneum (left external iliac artery) with metastases to the femoral lymph nodes was found in a 68-year-old woman at exploratory laparotomy. Light microscopy showed a typical alveolar pattern with fine vascular stroma. The tumor cells had finely granular eosinophilic cytoplasm and oval to round nuclei with pleomorphism and mitotic figures, Grimelius stain showed no argyrophilic granules, but S 100 protein was demonstrated in the cytoplasm by the PAP method of Sternberger. Formaling fixed tissues were examination by electron microscopy, and dense core granules consistent with neurosecretory granules were found in the cytoplasm of some tumor cells.