6436 Adrenal Venous Congestion Clinically Mimicking Carcinoma In A Large Degenerated Adrenocortical Adenoma

Abstract Disclosure: K. Ishiwata: None. S. Suzuki: None. S. Watanabe: None. Y. Yamazaki: None. H. Sasano: None. K. Yokote: None. Introduction: A large heterogenous adrenal tumor is often malignant. Only eight reported cases of adrenal adenoma harboring hemorrhage or venous thrombosis have been reported but their details not. We encountered a case of large degenerated adrenocortical adenoma harboring adrenal venous congestion mimicking adrenocortical carcinoma. Case: Adrenal tumor was incidentally detected in a 71-year-old woman with a history of hypertension, dyslipidemia, and osteoporosis in her regular health check-up. Abdominal CT and MRI demonstrated a heterogenous mass measuring 7.6 cm with peripheral enhancement in the left adrenal gland. [1]3[1]I-adosterol scintigraphy revealed accumulation only in the left tumor margins with no accumulation in [1]8F-FDG-PET scan. Results of endocrinologic evaluation were consistent with subclinical Cushing syndrome. The large size and heterogeneous nature of the mass clinically suggested adrenocortical malignancy, and left laparoscopic adrenalectomy was subsequently performed. The resected left adrenal lesion was encapsulated and measured 6.5 x 6.3 x 5.8 cm appearing almost black and partially yellow on the cut surface. Microscopically, the nodule was composed of SF-1 positive, clear cortical cells with abundant hyaline stroma containing numerous dilated veins with CD31/34-positive endothelial cells, and no foci of necrosis or hemorrhage were detected. The tumor cells above were positive for steroidogenic enzymes including CTP17, HSD3β and CYP11B1 but negative for CYP11B2. Ki-67 labeling index was <2% in the tumor. The criteria of Weiss (0 out of 9) revealed that the tumor was cortisol-producing adrenocortical adenoma. Discussion: In this case, clusters of SF1-positive cortisol producing adrenocortical adenoma cells were present in the hyalinized stroma containing many dilated blood vessels. These findings indicated that those histological features were caused by ischemic degeneration due to intratumoral circulatory disturbance, which clinically simulated adrenocortical carcinoma. Conclusion: We have experienced a very rare case of cortisol-producing adrenocortical adenoma with adrenal venous congestion, resulting in marked enlargement of the lesion. Presentation: 6/3/2024