Primary paraganglioma of the lung.

There are few reported cases of primary pulmonary paraganglioma in the pathology literature. Given the historical confusion surrounding bronchial tumors, widespread use of the term "chemodectoma" and classification of these lesions as paraganglioma in an outdated World Health Organization classification of lung tumors, the recognition of tumors arising from paraganglia within the lung has not been accepted by leading authorities. We present a well-documented case of a primary pulmonary paraganglioma with typical morphologic features and a supporting immunohistochemical profile. The 0.9 cm endobronchial tumor was submucosal and composed of nests of ovoid cells with abundant eosinophilic cytoplasm, cytoplasmic vacuoles, round to oval nuclei with speckled chromatin, and occasional conspicuous nucleoli. The nests of cells were surrounded by thin-walled vascular channels and stellate spindle cells. The ovoid cells showed strong diffuse staining for chromogranin A, synaptophysin, and faint staining for S-100; they were negative for cytokeratin AE1/AE3, Cam 5.2, and epithelial membrane antigen. The stellate spindle cells stained intensely positive for S-100 protein. A critical review of reported cases of pulmonary chemodectomas and paragangliomas in the English literature features few, if any, well-documented examples. While this exceedingly rare tumor should be discerned from carcinoid tumor, it remains unknown if primary pulmonary paragangliomas behave aggressively like intra-abdominal extra-adrenal paragangliomas, or in a more indolent manner observed with extra-adrenal paragangliomas in other locations.