Adrenal Mass Biopsy in Patients Without Extraadrenal Primary Malignancy: A Multicenter Study

BACKGROUND. Adrenal washout CT is not useful for evaluating incidental adrenal masses in patients without known or suspected primary extraadrenal malignancy. OBJECTIVE. The purpose of our study was to evaluate the diagnostic utility of adrenal mass biopsy in patients without known or suspected extraadrenal primary malignancy. METHODS. This retrospective six-center study included 69 patients (mean age, 56 years; 32 men, 37 women) without known or suspected extraadrenal primary malignancy who underwent image-guided core needle biopsy between January 2004 and June 2021 of a mass suspected to be arising from the adrenal gland. Biopsy results were classified as diagnostic or nondiagnostic. For masses resected after biopsy, histopathologic concordance was assessed between diagnoses from biopsy and resection. Masses were classified as benign or malignant by resection or imaging follow-up, and all nondi-agnostic biopsies were classified as false results. RESULTS. The median mass size was 7.4 cm (range, 1.9-19.2 cm). Adrenal mass biopsy had a diagnostic yield of 64% (44/69; 95% CI, 51-75%). After biopsy, 25 masses were resected, and 44 had imaging follow-up. Of the masses that were resected after diagnostic biopsy, diagnosis was concordant between biopsy and resection in 100% (12/12). Of the 13 masses that were resected after nondiagnostic biopsy, the diagnosis from re-section was benign in eight masses and malignant in five masses. The 44 masses with imaging follow-up included one mass with diagnostic biopsy yielding benign adenoma and two masses with nondiagnostic biopsy results that were classified as malignant by imaging follow-up. Biopsy had overall sensitivity and specificity for malignancy of 73% (22/30) and 54% (21/39), respectively; diagnostic biopsies had sensitivity and specificity for malignancy of 96% (22/23) and 100% (21/21), respectively. Among nine nondi-agnostic biopsies reported as adrenocortical neoplasm, six were classified as malignant by the reference standard (resection showing adrenocortical carcinoma in four, resection showing adrenocortical neoplasm of uncertain malignant potential in one, imaging follow-up consistent with malignancy in one). CONCLUSION. Adrenal mass biopsy had low diagnostic yield, with low sensitivity and low specificity for malignancy. A biopsy result of adrenocortical neoplasm did not reliably differentiate benign and malignant adrenal masses. CLINICAL IMPACT. Biopsy appears to have limited utility for the evaluation of incidental adrenal masses in patients without primary extraadrenal malignancy.