Unusual skin pigmentation after unilateral adrenalectomy due to pheochromocytoma: a case report

Background: Skin pigmentation after adrenalectomy occurs due to an increase in adrenocorticotropic hormone (ACTH) following adrenal insufficiency. ACTH-induced pigmentation usually appears as generalized hyperpigmentation and is known to appear after bilateral adrenalectomy. We report a case of unusual transient hyperpigmentation that developed immediately after unilateral adrenalectomy for pheochromocytoma and spontaneously resolved without corticosteroid supplementation.Case Description: A 29-year-old woman was admitted to the hospital due to sudden-onset chest pain and headache. A 2.8-cm left adrenal mass with heterogeneous enhancement was incidentally found in chest computed tomography during the evaluation. Multiple old infarctions were observed in brain magnetic resonance imaging (MRI), and left ventricular thrombi were found by echocardiography. Biochemical evidence confirmed the diagnosis of pheochromocytoma, while serum ACTH and cortisol levels were within normal ranges. The patient underwent laparoscopic left adrenalectomy via a posterior retroperitoneal approach and recovered without immediate postoperative complications. On day 3 after surgery, a crescent shaped cafe-au-lait skin pigmentation occurred on both the subcostal and the lumbar areas of the abdomen. Serial serum cortisol slightly decreased during the immediate postoperative period and recovered on day 3. Serum ACTH was elevated. Under close observation without corticosteroid supplementation, the pigmentation faded on day 8 after surgery. On day 15, the pigmentation clearly disappeared and serum ACTH decreased to within the normal range. A month later, ACTH and all adrenal hormones were within normal range.Conclusions: We hypothesized that skin pigmentation appeared due to an imbalance of the hypothalamic pituitary-adrenal (HPA) axis after resection of one adrenal gland. Skin pigmentation may be the first and early manifestation of adrenal insufficiency in patients who undergo unilateral adrenalectomy due to a nonCushing's tumor. Therefore, a careful physical examination may allow early detection of adrenal insufficiency and optimal treatment planning.