Pheochromocytoma presenting as fever of unknown origin, a case report

Introduction: Pheochromocytoma is a generally benign neoplasm derived from chromaffin cells of the adrenal medulla. It is characterized by the production of large amounts of catecholamines and also by the capacity to secrete bioactive peptides such as cytokines, mainly interleukin-1 (IL-1), interleukin-6 (IL-6) and TNF alpha.Case presentation: 24-year-old man, who consulted for fever, myalgia, and choluria. His laboratory tests were compatible with a systemic inflammatory response without infectious or autoimmune causes. However, a fluorodeoxyglucose positron emission tomography (FDGPET) revealed a left adrenal mass, without extra-adrenal lesions. On admission, increased levels of differentiated urine methanephrines, elevated baseline cortisol, non-suppressed adrenocorticotrophic hormone (ACTH), and positive low dose dexamethasone suppression test for cortisol were found. With suspicion of catecholamine and ACTH-producing pheochromocytoma, a tumor resection was performed, which conspicuously resolved all alterations of the inflammatory response. The histologic findings confirmed a pheochromocytoma, but the immunostaining for ACTH was negative. A literature review and the comparison of the findings with other reported cases allowed inferring that this was a case of interleukin-producing pheochromocytoma.Conclusion: Pheochromocytoma may be a cause of febrile syndrome, with IL-6 being the main mediator, which explains the manifestationsof systemic inflammation and ACTH-mediated hypercortisolism.