Malignant chemodectoma (paraganglioma) of the larynx. A case report with electron microscopy and biochemical assay.

This reports presents a case of malignant chemodectoma in the epiglottic region of a 47-year-old man. His initial complaint was laryngeal discomfort and he expired from generalized metastases of the tumor about one year after operation. The tumor was detected by laryngoscopy and laryngogram. The yellow parenchymatous tumor, 2.8 x 2.5 x 1.5 cm in size, was resected together with two enlarged regional lymph nodes. The mass was subjected to a histopathological study and biochemical assay. Microscopically, the tumor was located in the submucosa of the epiglottis and showed an alveolar growth pattern of comparatively uniform tumor cells. Neurosecretory granules were clearly demonstrated by Grimelius' method and by electron microscopy. The biochemical assay revealed that the tumor contained small amounts of serotonin, epinephrine, norepinephrine, and dopamine. The distribution of paraganglia as the source of these tumors, the clinicopathological review of the previous reports and significance of neurosecretory granules are discussed.