Objective: To determine the value of percutaneous adrenal biopsy in the evaluation of adrenal neoplasm.
Design: Retrospective review.
Setting: Tertiary referral center.
Patients: All adult patients undergoing image-guided adrenal biopsy from 1997 to 2007. Main Outcome Measure Biopsy sensitivity for malignancy.
Results: There were 163 biopsies performed on 154 patients. Mean (SD) age was 66 (12.5) years. Eighty-eight biopsies (53.4%) were performed in patients with a prior diagnosis of cancer. Forty-five (26.4%) were performed when imaging study results suggested previously undiagnosed cancer with a simultaneous adrenal metastasis. Thirty (20.2%) were performed for isolated adrenal incidentalomas. Rates of positive biopsy results in these 3 groups were 70.6%, 69.0%, and 16.7%, respectively. Prebiopsy evaluation for pheochromocytoma was performed in less than 5% of patients with established or suspected nonadrenal malignancies and 32% of patients with incidentalomas. In patients with isolated adrenal incidentaloma, a radiology report recommended biopsy 33% of the time for characteristics inconsistent with benign adenoma. Benign incidentalomas measured mean (SD) 4.2 (2.1) cm (range, 1.4-10.7 cm), and malignancies measured mean (SD) 9.3 (3.3) cm (range, 5.3-14 cm) (P < .05). All incidentalomas 5 cm or less (n = 18) were benign. There were 4 false-negative biopsy results: 3 adrenocortical carcinomas and 1 pheochromocytoma.
Conclusions: Biopsy is unhelpful in patients with isolated adrenal incidentaloma. Despite atypical radiographic findings, all nonfunctioning nodules 5 cm or less were benign. The negative predictive value is unacceptably low and cannot be relied on to rule out malignancy. The value of biopsy remains the diagnosis of metastatic carcinoma in patients with a nonadrenal primary malignancy, proven by the more than 70% positive rate in this group.