Diagnostic challenges in the fine-needle aspiration diagnosis of carotid body paragangliomas: report of two cases.

Two cases of carotid body paragangliomas sampled by fine-needle aspiration (FNA) cytology prior to other medical diagnostic studies are presented. In the first case, the presence of an ipsilateral ulcerative lesion of the nasopharynx along with pronounced atypia of the specimen posed a challenge to the correct cytologic interpretation, which was initially sidetracked in favor of a metastatic epithelial lesion. In the second case, a tumor mass of unusually large size and extension which included the pharynx, coupled with a large amount of profusely hemorrhagic aspirate, presented a diagnostic problem, which was overcome by processing part of the specimen as a cell block, which by its histologic and immunochemical features provided a definitive pathologic diagnosis. In handling these two clinically complex cases of carotid paraganglioma, two learning principles became clear on how to reach a correct FNA diagnosis in such lesions: 1) The anatomic location of the lateral neck mass with its prolonged history, along with a hemorrhagic FNA specimen exhibiting at least some cytologic features reminiscent of endocrine neoplasm, are among the factors that help in arriving at a suggestive diagnosis of paraganglioma, when other clinical features tend to sidetrack from interpretation of the cytologic changes. 2) In the practice of FNA cytology, if the possibility of paraganglioma arises, processing part of the specimen as a cell block with accompanying histology and immunohistochemistry can provide a definitive diagnosis of such lesion.