Abstract
Pheochromocytoma is a tumor of chromaffin cells causing catecholamines overproduction. Interleukin-6 (IL-6), a cytokine, is central to inflammation and immunity. Few studies have reported IL-6-producing pheochromocytoma whose underlying mechanism has not been elucidated. Herein, we present a case of pheochromocytoma whose clinical manifestations changed, and IL-6 levels elevated over time. A 48-year-old woman was referred to our hospital for fever and hepatic dysfunction. Six years prior, a right adrenal tumor was detected during the examination for ovarian teratoma without C-reactive protein (CRP) elevation. Several imaging studies at our hospital showed no abnormalities except for an increase in the size of the adrenal tumor and hepatomegaly. In addition, antibiotics did not improve the fever. Laboratory tests showed elevated levels of CRP with IL-6 elevation. An enlarged adrenal tumor was detected. Administering doxazosin lowered the CRP and IL-6 levels, then IL-6-producing pheochromocytoma was suspected, and adrenalectomy was performed. After surgery, fever and hepatic function were improved, and the CRP and IL-6 levels were normalized. Immunostaining of the resected tissue showed IL-6 focal positivity, which meant the phenotype of tumor cells focally changed their phenotypes over time. IL-6-producing pheochromocytoma should be considered in patients with adrenal tumors and fever of unknown origin.