Clinical and pathological features of oncocytic adrenocortical carcinoma: a retrospective comparative study

Adrenocortical carcinoma (ACC) is a rare tumor with highly aggressive malignancy. Its two main pathological subtypes, conventional ACC (CAC) and oncocytic ACC (OAC), are hypothesized to differ in clinical behavior, but comparative studies are limited due to the rarity of OAC. This study aimed to compare the clinical characteristics, pathological features, and prognosis between CAC and OAC.

A retrospective review was conducted on 128 ACC patients (105 CAC, 23 OAC) during the period of October 2015 and October 2025. Data on clinical presentation, hormonal status, pathological findings, and survival outcomes were collected and analyzed. Statistical comparisons were performed using t-tests, Mann-Whitney U tests, chi-square tests, Cox proportional hazards regression analysis, multivariable Cox proportional hazards regression analysis, and Kaplan-Meier survival analysis with log-rank test.

Compared with CAC, OAC patients had a significantly lower prevalence of Cushing's syndrome (13.0% vs. 39.0%, P < 0.05) and hypertension (17.4% vs. 48.6%, P < 0.01). In contrast, adrenal-derived sexual characteristics abnormalities were more common in OAC (65.2% vs. 26.0%, P < 0.001). Pathologically, compared with CAC, the Ki-67 index was significantly lower in OAC (median: 14% vs. 20%, P < 0.05). Also, Kaplan-Meier survival analysis revealed a more favorable overall survival(OS) for OAC, with a 5-year OS rate of 70.4% compared to 48.4% for CAC (P < 0.05). After multivariate adjustment for ENSAT stage and Ki‑67, pathological subtype lost independent prognostic significance, while ENSAT stage and Ki‑67 remained independent predictors.

CAC was associated with a higher frequency of glucocorticoid excess symptom, a higher proliferative index (Ki-67). OAC was characterized by a higher prevalence of androgen excess symptoms. OAC demonstrated similar OS to CAC after adjustment for ENSAT stage and Ki‑67.