Meta-[I-131]iodobenzylguanidine uptake in a nonsecreting paraganglioma

In a patient with a paraganglioma at the carotid bifurcation, intense uptake of meta-[I-131]iodobenzylguanidine (I-131 MIBG) in the tumor was found. There was no clinical or biochemical evidence for catecholamine secretion by the tumor, although analysis of the tissue revealed that catecholamine biosynthesis took place. We conclude that accumulation of I-131 MIBG may occur in a paraganglioma, but does not necessarily indicate endocrine activity of the tumor.