Oncocytic subtypes of adrenal cortical carcinoma: Aggressive in appearance yet more indolent in behavior?

Adrenal cortical carcinoma is an aggressive malignancy and typically heralds a poor prognosis. The oncocytic subtype of this neoplasm is rare but may be associated with more favorable outcomes. The Provincial Cancer Registry was searched for cases of adrenal cortical carcinoma between 1992 and 2017. Comprehensive chart reviews were performed and data gathered related to presentation, treatment, and outcomes. In the study, 82 patients with adrenal cortical carcinoma were identified. Complete data were available for 67 patients (82%). In the 41 patients who underwent resection, 9 (22%) had oncocytic subtypes. When compared with the total group of adrenal cortical carcinomas, the oncocytic subtypes were larger at presentation (19.8 cm vs 11.0 cm), more commonly symptomatic and hormonally active, and despite larger tumor size, were often early stage I and II. Recurrent disease was observed in 3 out of 9 oncocytic subtype (vs 23 out of 32 adrenal cortical carcinoma), with greater median time to recurrence (17.5 vs 8 months). Univariate analysis suggested that age, T-stage, M-stage, and overall stage were associated with survival. There was a trend toward improved overall survival for patients with oncocytic subtype on Kaplan-Meier and multivariate analysis. Despite our small numbers of patients with oncocytic subtype, our data suggest that oncocytic subtype are typically larger at presentation but more often early stage and recur less frequently than adrenocortical carcinomas. Modifications to treatment and surveillance strategies may be appropriate in this subtype.