Ectopic ACTH-Producing Pheochromocytoma as a Rare Cause for Rapid Progressing Cushing Syndrome: A Case Report

Background: Cushing syndrome due to ectopic CRH or ACTH secretion can be rarely caused by pheochromocytoma, commonly as part of genetic conditions. Case: A 21 year-old male, previously healthy, with no usual medication, went to the physician assistant for hematuria. The kidney US revealed, besides lithiasis, a highly vascularized mass in the right adrenal gland with 10 cm. In his first evaluation the patient had no complaints or pheochromocitoma/hypercortisolism stigmata, other than hand tremor and slight rounding of the face. Blood pressure was 149/88 mmHg, and heart rate 86 bpm. There was no family history of endocrine disease. He rapidly developed increased appetite, insomnia, and severe myalgias, with filling of supraclavicular fossae, facial plethora, and cervical and truncal acne. Laboratory analysis showed abnormal overnight dexamethasone suppression test (57.4 µg/dL, N < 1.8), elevated ACTH 378 pg/mL (N 9.0–52.0), 24h-urinary free cortisol (UFC) (5334.0 µg/24h, N 4.3–176.0), and late-night salivar cortisol (1.44 µg/dL, N < 0.32), hypokalemia (2.8 mEq/L, N 3.8–5.0), and leukocytosis (22.4*10(9)/L, N 4.0–11.0); DHEA-S 962 µg/dL (N 80–560), 4-androstenedione 380 ng/dL (N 70–360), 17-OH progesterone 4.5 ng/mL (N 0.59–3.44), cromogranine A 6063 ng/mL (N 0–100), and markedly elevated urinary amines (adrenaline 173 nmol/24h, N 0–109; noradrenaline 5033 nmol/24h, N 89–473; normetanephrine 334605 nmol/24h, N 480–2424; metanephrine 15998 nmol/24h, N 264–1729; dopamine 4808 nmol/24h, N 424–2612). Hypercalcemia with hypophosphatemia and supressed PTH level was also detected. 68Ga-DOTANOC PET revealed a mass of the right adrenal gland with overexpression of somatostatin receptors (likely pheochromocytoma), without evidence of other tumor lesions of neuroendocrine origin. Pituitary MRI showed normal pituitary gland. Potassium supplementation, alpha-blockade with phenoxybenzamine, and metyrapone were initiated. Due to severe back pain, a CT scan of the spine was performed detecting compressive osteoporotic fractures in the mid dorsal and low dorsal segments. The patient was submitted to right adrenalectomy. Histology revealed pheochromocytoma with 11.2*9mm, with capsular and vascular invasion, extra-adrenal extension, necrosis, and atypical mitosis, with Ki67 of 9.5% and PASS score of 16. Postoperative analysis showed ACTH 45.6 pg/mL (N 7.2-63,3), late-night salivar cortisol < 0,0544 µg/dL (N < 0,32) and free urinary cortisol 41.4 µg/24h (N 4.3–176.0). Discussion: Ectopic cushing syndrome caused by pheochromocytoma is a rarely described entity. In this young patient, it caused rapid clinical progression of hypercortisolism with important hydroelectrolytic disturbances and compressive vertebral fractures, requiring prompt surgical intervention for clinical remission and improvement.