HYPERTENSION AND A TUMOR OF THE GLOMUS-JUGULARE REGION - EVIDENCE FOREPINEPHRINE BIOSYNTHESIS

Glomus jugulare tumors have been reported to secrete norepinephrine an d cause severe hypertension with features similar to pheochromocytoma. In contrast, epinephrine secretion has not been observed in these neo plasms. This has been attributed to the absence of the norepinephrine- methylating enzyme, phenylethanolamine-N-methyltransferase (PNMT), req uired for epinephrine synthesis. We report a patient with severe hyper tension caused by a glomus tumor that secreted norepinephrine and epin ephrine. Following selective venous sampling, catecholamines were quan tified by radioenzymatic assay. Marked elevations in norepinephrine an d epinephrine release were localized to the glomus tumor. The enzymes involved in catecholamine biosynthesis, including PNMT and tyrosine hy droxylase, were identified immunocytochemically in the tumor. The glom us tumor had staining patterns identical to those observed within norm al rat glomus cells. Hypertension resolved with resection of the funct ioning tumor. This is the first report of PNMT in a functioning paraga nglioma of the glomus jugulare region. The factors that determine why functional activity is expressed only rarely by paraganglioma remain u ndefined.