An ectopic adrenocortical adenoma in renal hilum presenting with Cushing's syndrome

Rationale: Ectopic adrenal tissue is the adrenal rests along the path from gonads to adrenal glands during embryogenesis. Ectopic adrenocortical adenoma is a rare disease represented with over-production of cortisol by the ectopic adrenocortical tissue. Patient concerns: An 18-year-old Chinese female patient was presented with weight-gain for 6 months. She had elevated plasma cortisol and a solitary mass was revealed using computed tomography scan in the left renal hilum. Diagnosis: The tumor was removed and the immunohistochemical profile indicated an ectopic adrenocortical adenoma. Interventions: After the tumor was removed, the patient was under glucocorticoid replacement therapy in 6-month. Outcomes: During 6-month of follow-up, the patient showed no signs of tumor recurrence. Lessons: Ectopic adrenocortical adenoma is difficult to diagnose due to its low incidence, and the ectopic rests in renal hilum could be misdiagnosed as renal cell carcinoma. This case reminds clinicians to be aware of ectopic site in the diagnosis of adrenocorticotropic hormone (ACTH) independent Cushing's syndrome. Immunohistochemical stain may assist in evaluating the origin of the ectopic rests. A certain rate of local recurrence indicated the need of long-term follow-up.