A RARE CASE OF CATASTROPHIC CUSHING'S SYNDROME DUE TO ACTH-SECRETING PHEOCHROMOCYTOMA: CHALLENGES IN THE DIAGNOSTIC JOURNEY.

Context: Pheochromocytomas are very rare but important and potentially life-threatening sources of ectopic ACTH secretion (EAS), and the diagnosis of Cushing's syndrome due to adrenocorticotropic hormone (ACTH)-producing pheochromocytoma needs a high index of suspicion. Case presentation: Herein, we present a rare case of catastrophic Cushing 's syndrome due ACTH-producing pheochromocytoma in a 59-year-old woman, which was characterized by severe hypercortisolism, markedly elevated ACTH levels and rapidly progressed and persisting metabolic derangements, and complete resolution of symptoms and signs after adrenalectomy, despite no biochemical evidence of pheochromocytoma and the coexisting adrenal cortical adenoma. The timely recognition of findings sufficient to raise the suspicion of an ACTH-producing pheochromocytoma is crucial to plan surgical resection of the adrenal mass which is the only curative option enabling quick recovery with complete amelioration of symptoms and signs and restoration of organ functions. Conclusions: In this regard, our case highlights the likelihood of severe hypercortisolism even in the absence of typical Cushingoid features, and the consideration of suspected diagnosis of ACTH-releasing pheochromocytoma even in the absence of biochemical evidence on catecholamine hypersecretion when workup is suggestive of an ectopic source along with an adrenal mass on imaging.