Imaging appearance of renal epithelioid angiomyolipomas.

Objective: This study aimed to describe the computed tomographic (CT) imaging appearance of renal epithelioid angiomyolipomas (eAMLs).
Methods: The CT scans and electronic medical records of 8 patients with histologically confirmed eAMLs identified by biopsy and/or surgical excision who had available imaging performed between 1995 and 2012 were reviewed. Preoperative CT imaging appearance, histologic features, and clinical follow-up were recorded for each patient.
Results: Macroscopic fat was identified in 3 (38%) of 8 eAMLs on preoperative CT imaging. Seven of the eAMLs demonstrated postcontrast enhancement of greater than 20 Hounsfield units. None of the eAMLs showed evidence of local invasion, vascular involvement, or distant metastases on the initial preoperative CT; however, 1 patient developed local recurrence and another developed distant metastatic disease on follow-up imaging.
Conclusions: Epithelioid angiomyolipomas may or may not demonstrate macroscopic fat. Those with macroscopic fat do not possess any CT imaging characteristics that allow them to be distinguished from typical angiomyolipomas. Epithelioid angiomyolipomas without macroscopic fat are indistinguishable from renal cancers.