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The cytology of bronchial brushings from a malignant paraganglioma metastasizing to the lung

The paraganglia system includes the adrenal medulla and the extra-adrenal system and can be divided broadly into the parasympathetic system and the orthosympathetic system. Tumours arising from these structures are called paragangliomas. The majority occur in the head and neck and are usually benign. Retroperitoneal paragangliomas can occur anywhere along the paravertebral chain, often in close proximity to the adrenal gland. About 10% of all paragangliomas behave in a malignant fashion; the incidence of malignancy is quoted as between 28% and 42% in paragangliomas arising in the retroperitoneum. There are reports of primary pulmonary paragangliomas, but some authorities view these reports as controversial and consider that suspicion of a metastasis from an extrapulmonary paraganglioma to lung should always be high. We describe a case in which the transbronchial biopsy was of limited diagnostic help, but the bronchial brushing cytology, taken at the same time, revealed an unusual population of malignant cells displaying neuroendocrine features and raising the possibility of metastatic malignancy rather than the clinically suspected primary bronchial carcinoma. This prompted a search for the primary which was reported as a malignant paraganglioma arising in the retroperitoneum. While the fine needle aspiration (FNA) cytological features of paragangliomas are well described, we can find no other description of the features in bronchial brush cytology. We wish to demonstrate some features which help in the distinction from primary bronchial carcinoma.