Cystic paraganglioma of the anterior mediastinum.

Paraganglioma of the mediastinum is an extremely uncommon neoplasm, and the concurrent finding of cystic changes has yet to be reported in the literature. We report a case of a 43-year-old man presenting with chest pain and left arm paresthesias. Imaging studies revealed a well-defined cystic lesion located in the anterior mediastinum, with the patient undergoing subsequent surgical resection of the mass. Grossly, the heterogenous mass measured 6.0 × 3.6 × 1.7 cm, with prominent cystic spaces and scattered solid areas. Microscopic examination revealed pseudocystic spaces with proliferation of large epithelioid cells with abundant eosinophilic cytoplasm, moderate pleomorphic nuclei, and prominent nucleoli, in a nested pattern of growth along the cysts walls. Immunohistochemical stains showed strong positivity for chromogranin, synaptophysin, and CD56 in the epithelioid cells, with negative staining for cytokeratin AE1/AE3, confirming the diagnosis of paraganglioma. S-100 was positive in the intervening sustentacular cells throughout the tumor. Cystic paraganglioma of the anterior mediastinum is a rare neoplasm, which , to our knowledge, has not yet been reported in the English literature, and should be added to the differential diagnosis of cystic lesions of the mediastinum.