Differences in Clinicopathologic Behavior of Oncocytic Adrenocortical Neoplasms and Conventional Adrenocortical Carcinomas

Background: Oncocytic adrenocortical neoplasms (OANs) are rare endocrine tumors that present as a spectrum from benign to malignant. The outcomes after surgical resection of the oncocytic variant of adrenocortical carcinoma remain poorly understood. We sought to characterize the clinicopathologic features of OAN and compare oncocytic adrenocortical carcinoma (OAC) with conventional adrenocortical carcinoma (ACC). Patients and Methods: Adult patients who underwent adrenalectomy for OAN or ACC between January 1990 and September 2020 were identified. Demographics, clinicopathologic factors, American Joint Committee on Cancer stage, and cancer-related outcomes were reviewed. A matched cohort analysis of disease-free survival (DFS) and overall survival (OS) was performed between patients with OACs and those with ACCs. Results: Forty-one patients with OAN and 214 patients with ACC were included. The OAN cohort median age was 45.2 years [interquartile ratio (IQR) 38.5–54.0 years], and 61.0% were female. OANs were benign (n = 11), of uncertain malignant potential (UMP, n = 9), or OAC (n = 21). Disease recurrence occurred in 12 (57.1%) patients with OAC compared with 1 (11.1%) and 0 patients with UMP or benign OAN, respectively (p < 0.001). Seven (33.3%) patients with OAC died during follow-up compared with 0 patients with UMP or benign OAN (p = 0.020). Kaplan–Meier survival analysis found no difference in DFS between ACC and OAC groups before (p = 0.218) and after 2:1 matching (p = 0.417). Overall survival was shorter for patients who had ACC compared with those who had OAC (p = 0.031), but the difference was not evident with matched analysis (p = 0.200). Conclusions: OAN presents as a spectrum from benign indolent tumors to aggressive carcinomas. OACs demonstrate similar clinicopathologic behavior and recurrence-free and overall survival when matched to conventional ACCs.