Ovarian paraganglioma.

A rare case of ovarian paraganglioma was incidentally found as a 1.2-cm intraovarian mass in a 68-year-old hypertensive female operated for an endometrial carcinoma. Histologically, it was arranged in characteristic Zellballen composed of polygonal clear cells with a granular cytoplasm that expressed diffusely CAM5.2 cytokeratin, chromogranin, neuron-specific enolase, synaptophysin, and CD56, while S-100 protein was only present in sustentacular cells. We analyzed differential diagnoses with other rare ovarian tumors such as Sertoli cell tumor, with which it may share an immunophenotype expressing cytokeratins, S-100, and other neural markers, and extra-axial ependymoma, which invariably expresses diffusely GFAP, that may be positive only in the sustentacular cells of paraganglioma. However, on simple hematoxylin-eosin inspection, ovarian paraganglioma displays characteristic Zellballen clusters and cells with a granular cytoplasm but lacks the distinctive Sertoli cell tubules and the characteristic rosettes and fibrillary cytoplasm of ependymoma. Pathologists should be aware of the unusual locations of paraganglioma.