Periadrenal mature cystic teratoma mimicking adrenal myelolipoma: a case report and review of the literature.

Mature teratomas arising in the adrenal region are rare and may mimic adrenal myelolipomas, particularly when adipose tissue is predominant. A 72-year-old woman with uncontrolled hypertension was found to have an 8.6-cm fat-containing mass in the right adrenal region, radiologically diagnosed as an adrenal myelolipoma. Laparoscopic adrenalectomy was performed. Histologically, the tumor predominantly consisted of mature adipose tissue with scattered epithelial-lined cystic structures, neural tissue, cartilage, thyroid tissue, bone marrow elements, and smooth muscle, confirming a mature cystic teratoma. Only a small amount of compressed adrenal tissue was identified at the tumor periphery without direct histologic continuity, supporting a periadrenal retroperitoneal origin. This case highlights that fat-dominant mature teratomas can closely mimic adrenal myelolipomas and should be considered in the differential diagnosis of heterogeneous fat-containing masses in the adrenal region.