Adrenal rest tumor of the broad ligament: Case report with immunohistochemical study of steroidogenic enzymes

An adrenal rest tumor of the broad ligament was studied in a 43-year-old woman. The tumor measuring 6x3x3 cm and appearing as golden-yellow on the cut surface was incidentally discovered during a total hysterectomy due to uterine leiomyoma. The encapsulated tumor predominantly composed of pale and lipid-rich arranged in alveolar clusters or short blunt cords. Electron microscopic examination revealed mitochondria with tubulo-vesicular cristae and abundant lipid droplets. Adrenal 4-binding protein, a transcriptional factor of steroidogenesis, was present in almost all of the tumor cells, suggestive of steroidogenic features in the lesion. Immunoreactivity of steroidogenic enzymes involved in adrenocortical steroid production was detected in the tumor cells, suggesting that tumor cells had the potential to synthesize adrenocortical steroids. A relatively low Ki-67 labeling index (3.20+/-1.15 per 100 tumor cells) and an absence of necrosis and vascular and/or capsular invasion suggest benignity of the lesion.