Clinical, biochemical, and radiological characteristics of a single-center retrospective cohort of 705 large adrenal tumors

Objective: To characterize large adrenal tumors (≥4 cm) and to identify features associated with malignancy. Patients and Methods: We investigated the clinical, biochemical, and imaging characteristics in a large retrospective single-center cohort of patients with adrenal tumors ≥4 cm during the period of January 1, 2000 through December 31, 2014. Results: Of 4085 patients with adrenal tumors, 705 (17%) had adrenal masses ≥4 cm in diameter; 373 (53%) were women, median age was 59 years (range, 18-91), and median tumor size was 5.2 cm (range, 4.0-24.4). Underlying diagnoses were adrenocortical adenomas (n=216, 31%), pheochromocytomas (n=158, 22%), other benign adrenal tumors (n=116, 16%), adrenocortical carcinomas (n=88, 13%), and other malignant tumors (n=127, 18%). Compared to benign tumors, malignant tumors were less frequently diagnosed incidentally (45.5% vs 86.7%), were larger (7 cm [range, 4-24.4] vs 5 cm [range, 4-20]), and had higher unenhanced CT attenuation (34.5 HU [range, 14.1 to 75.5] vs 11.5 HU [range, -110 to 71.3] (P<.001). On multivariate analysis, older age at diagnosis, male sex, non-incidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were all statistically significant predictors of malignancy. Conclusions: Prevalence of malignancy in patients with adrenal tumors ≥4 cm was 31%. Older age, male sex, non-incidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were associated with an increased risk for malignancy. Clinical context should guide management in patients with adrenal tumors ≥4 cm in diameter.