Malignant paraganglioma of retroperitoneum light, electron microscopic and ultrasonographic study

Abstract

A malignant retroperitoneal nonchromaffin paraganglioma in a thirty-four-year-old man was studied by light and electron microscopy. Histologically, the tumor cells displayed a tendency to surround granular, eosinophilic intercellular material and to form nests and pseudoacini. Ultrastructurally, the tumor was composed of moderately well-differentiated epithelial cells intermixed with sparse sustentacular cells. An organoid pattern, reminiscent of the functional anatomic unit of nonchromaffin paraganglia, was seen occasionally. Epithelial cells formed pseudoacini around dilated interstitial spaces and rosettes around cytoplasmic masses composed of interdigitating microvillous processes. These morphologic features are consistent with the neurocrestal origin of paragangliomas. The patient died ten months after presentation despite an initial favorable response to irradiation.