Pheochromocytoma as a frequent false-positive in adrenal washout CT: A systematic review and meta-analysis

Objective To evaluate the proportion of pheochromocytomas meeting the criteria for adenoma on adrenal washout CT and the diagnostic performance of adrenal washout CT for differentiating adenoma from pheochromocytoma. Methods MEDLINE and EMBASE were searched to 28 March 2017. We included studies that used adrenal washout CT for characterisation of pheochromocytomas. Two independent reviewers assessed the methodological quality using Quality Assessment of Diagnostic Accuracy Studies-2. Proportions were pooled using an inverse variance method for calculating weights (random-effects). Sensitivity and specificity were pooled using hierarchical logistic regression modelling and plotted in a hierarchical summary receiver-operating-characteristics (HSROC) plot. Results Ten studies (114 pheochromocytomas) were included. The pooled proportion of pheochromocytomas meeting the criteria for adenomas was 35 % (95 % CI 20–51). For eight studies providing information on diagnostic performance, the pooled sensitivity and specificity for differentiating adenoma from pheochromocytoma were 0.97 (95 % CI 0.93–0.99) and 0.67 (95 % CI 0.44–0.84), respectively. The area under the HSROC curve was 0.97 (95 % CI 0.95–0.98). Conclusions There was a non-negligible proportion of pheochromocytomas meeting the criteria for adenoma on adrenal washout CT. Although overall diagnostic performance was excellent for differentiating adenoma from pheochromocytoma, specificity was relatively low. Key Points • Non-negligible proportion of pheochromocytomas can be mistaken for adenoma. • Adrenal washout CT showed good sensitivity (97%) but relatively low specificity (67%). • Findings other than washout percentage should be used when diagnosing pheochromocytomas