FINE-NEEDLE ASPIRATION CYTOLOGY OF MALIGNANT RETROPERITONEAL PARAGANGLIOMA

The cytologic findings in a fine-needle aspiration sample are describe d from a large retroperitoneal mass in a 56-yr-old male. The aspiratio n was performed under CT guidance using a 22-gauge needle, maintaining negative pressure. For cytologic study, on-site smears were prepared and stained by the Papanicolaou method. Additionally, cytospin, filter preparations, cell blocks from the aspirate, histology, and electron microscopy of the tumor tissue were performed. Also, immunodiagnostic staining for neuron-specific enolase (NSE), chromogranin, S-100 protei n, vimentin, HMB45, cytokeratin, and Grimelius preparation was perform ed on cytologic and histologic material. The cytologic material was ch aracterized by cords, suggestive acinar structures, and small follicle -like clusters of cells, while cell blocks from aspirate showed oval o r spindle-shaped nuclei with a somewhat fasciculated appearance. Howev er, sections from the tumor tissue showed an organoid ''zellballen'' p attern. The nuclei were round, oval, spindly, and epithelioid, with mo derate to scanty cytoplasm, smooth nuclear membranes, fine, evenly dis persed chromatin, slight hyperchromasia, and mild pleomorphism. No int ranuclear vacuoles were seen. Positive immunohistochemical staining fo r NSE, chromogranin, and Grimelius preparation was noted in the tumor cells, while staining for vimentin, HMB45, and cytokeratin was negativ e. Electron microscopy of the tumor tissue revealed the presence of va riable numbers of round, membrane-bound, electron-dense neurosecretory granules. The cytohistologic and ultrastructural findings are present ed, as well as the results of immunodiagnostic staining which helped i n the diagnosis of retroperitoneal paraganglioma, an infrequently repo rted tumor. (C) 1998 Wiley-Liss, Inc.