Hypertension and a tumor of the glomus jugulare region. Evidence for epinephrine biosynthesis.

Overview

Glomus jugulare tumors have been reported to secrete norepinephrine and cause severe hypertension with features similar to pheochromocytoma. In contrast, epinephrine secretion has not been observed in these neoplasms. This has been attributed to the absence of the norepinephrine-methylating enzyme, phenylethanolamine-N-methyltransferase (PNMT), required for epinephrine synthesis. We report a patient with severe hypertension caused by a glomus tumor that secreted norepinephrine and epinephrine. Following selective venous sampling, catecholamines were quantified by radioenzymatic assay. Marked elevations in norepinephrine and epinephrine release were localized to the glomus tumor. The enzymes involved in catecholamine biosynthesis, including PNMT and tyrosine hydroxylase, were identified immunocytochemically in the tumor. The glomus tumor had staining patterns identical to those observed within normal rat glomus cell. Hypertension resolved with resection of the functioning tumor. This is the first report of PNMT in a functioning paraganglioma of the glomus jugulare region. The factors that determine why functional activity is expressed only rarely by paraganglioma remain undefined.