A Rare Case of Adrenocorticotropic Hormone (ACTH)-Secreting Pheochromocytoma Presenting With Severe Cushing Syndrome (CS) and Dual Hormonal Secretion.

We present a rare case of a 58-year-old woman diagnosed with an adrenocorticotropic hormone (ACTH)-secreting pheochromocytoma, manifesting as severe Cushing syndrome (CS) with dual-hormonal secretion. She had a three-week history of upper-body tremors, hyperglycemia, hypokalemia, and new-onset, treatment-resistant hypertension. Biochemical investigations revealed markedly elevated cortisol, ACTH, and catecholamine levels. Imaging identified a 3.4 cm enhancing left adrenal mass, and further functional imaging and hormonal assays confirmed the diagnosis. She underwent laparoscopic adrenalectomy following medical stabilization with alpha-blockade and metyrapone. Histopathology confirmed a low-risk pheochromocytoma with positive ACTH immunostaining. Postoperatively, the patient had complete resolution of hypercortisolism, normalization of metabolic parameters, and significant clinical improvement. This case highlights the importance of recognizing dual-hormonal secretion in adrenal tumors, as early detection allows safer preoperative optimization and reduces perioperative risk. It also emphasizes maintaining a high index of suspicion for ectopic ACTH production in rapidly progressing CS. Early diagnosis and appropriate preoperative management are critical to reducing morbidity and mortality.