Aspiration biopsy of osseous metastasis of retroperitoneal paraganglioma -Report of a case with cytologic features and differential diagnostic considerations

BACKGROUND: Paragangliomas are uncommon tumors, only 10% of which ave malig nant, as evidenced by metastatic disease. It is rare for paraganglioma to p resent with symptomatic osseous metastases. CASE: A retroperitoneal paraganglioma presented in a 52-year-old man as pai nful metastases in the rib and vertebrae. Fine needle aspiration (FNA) of a lumbar vertebral lesion showed cells arranged singly and in loose clusters with fragile, vacuolated or finely granular cytoplasm, marked anisonucleos is and mitoses. Rare zellballen-type structures and intranuclear inclusions were present. Immunohistochemical studies of a subsequent FNA core biopsy of the retroperitoneal mass showed strong immunoreactivity with chromograni n and negative staining for keratin; that was helpful in differentiating th is tumor from others in the diffrential diagnosis. CONCLUSION: The cytologic diagnosis of paraganglioma is difficult as these tumours exhibit a plethora of features that overlap those of many other neo plasms. The diagnosis can be confirmed with appropriate immunohistochemical studies of corresponding core biopsies.