Macroscopic Fat in Adrenocortical Carcinoma: A Systematic Review

OBJECTIVE. The objective of this systematic review was to determine the number and quality of reports of adrenocortical carcinoma (ACC) containing macroscopic fat; this information may inform guidelines for diagnosis and management of ACC. MATERIALS AND METHODS. A comprehensive search of databases of published studies was performed. Two reviewers independently selected original research, case series, or case reports of ACC with macroscopic fat on imaging and extracted data. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. RESULTS. Three case reports and one retrospective study comprising a total of seven cases of ACC (lesion size: range, 6.5-22 cm) with macroscopic fat were included. ACC was symptomatic in all patients; neither locally invasive features nor metastases were reported. Four cases had less than 5% macroscopic fat on imaging, and the percentage fat on imaging was not reported for the remaining three cases. With regard to the risk of bias, one case had high risk for the index test domain because of potentially unreliable determination of macroscopic fat (i.e., no pathologic confirmation). All seven cases (from four studies) had unclear risk for the reference standard domain because there was insufficient information about the reference standard to determine whether ACC was correctly diagnosed. All studies were at low risk of bias in the flow and timing domain. CONCLUSION. There are few reports of macroscopic fat in ACC detected on imaging studies; among the reports of macroscopic fat in ACC, tumors were large (> 6 cm) and had a small proportion of gross fat (< 5%). The reliability of reported cases is questionable primarily because of insufficient details about pathologic diagnosis. Based on this information, a change in guideline recommendations may not be warranted. However, consideration of follow-up or biopsy of patients with large symptomatic tumors (> 6 cm) containing a small proportion of fat (< 5%) may be appropriate.