Metastatic Pheochromocytoma/Paraganglioma Overproducing Multiple Catecholamines

Pheochromocytoma and paraganglioma (PPGL) are rare chromaffin-cell tumors producing adrenaline and/or noradrenaline, or solely dopamine. A 52-year-old man presenting with hypertension (141/79 mm Hg) and weight loss (10 kg in 6 months) was admitted to our hospital. Computed tomography revealed a massive right adrenal mass (150 mm) with partial necrosis, accompanied by multiple liver nodules. These nodules showed a high signal intensity on T2-weighted magnetic resonance imaging. Subsequently, a diagnosis of PPGL was made based on elevated urinary excretion of adrenaline (355 µg/day [1937 nmol/day]; normal range: 3.4-26.9 µg/day; 18-146 nmol/day), noradrenaline (1690 µg/day [9989 nmol/day]; normal range: 48.6-168.4 µg/day; 287-995 nmol/day), and dopamine (53 000 µg/day [258 322 nmol/day]; normal range: 365-961.5 µg/day; 1779-4686 nmol/day). The ¹²³I-metaiodobenzylguanidine scintigraphy and fluorodeoxyglucose positron emission tomography scan showed heterogenous uptake among the adrenal and the liver foci, respectively. Clustering analysis of previous PPGL cases highlighted the unique catecholamine profile of this case. These findings suggest a possibility that internodular heterogeneity between primary and metastatic foci on nuclear imaging may indicate varying differentiation grades and resultant catecholamine secretion. Further studies will be needed to verify these results and confirm this hypothesis.