Extensive Fever of Unknown Origin (FUO) Workup to Unmask Pheochromocytoma.

Pheochromocytoma is a tumor arising from chromaffin cells of the medulla of adrenal gland and secretes excessive amounts of catecholamines: epinephrine and norepinephrine. It can also arise from sympathetic ganglia when it is referred to as catecholamine-secreting paragangliomas or extra-adrenal pheochromocytoma. Pheochromocytoma has been referred to as "the masquerader" for its numerous atypical presentations, which makes its diagnosis medically challenging. Here, we present a case of a 66-year-old female, presenting with high-grade fever for two weeks associated with generalized body aches. She had an extensive infectious, rheumatological and hematological workup. Ultimately, she was diagnosed with pheochromocytoma. After adrenalectomy, her fever and body ache resolved.