Multiple biliary hamartomas: magnetic resonance features with histopathologic correlation.

The purpose of this study was to report the magnetic resonance imaging (MRI) features of multiple biliary hamartoma (MBH) and to correlate them with histopathology. MRI features of 11 patients with MBH proven by histology were retrospectively reviewed and correlated to histopathology. MBH presented as multiple, tiny, and uniformly distributed lesions in all cases. All were hypointense on T1-weighted images and hyperintense on T2-weighted images relative to the liver parenchyma. Mural nodules were identified in 10 of 11 (91%) cases. They were isosignal on T1-weighted images, intermediate signal on T2-weighted images. Gadolinium-enhanced images showed mural nodule enhancement in 9 of 10 patients (90%) or a peripheral rim-like enhancement of the whole lesion in one case (9%). MBH were present in all liver specimens. In the six patients examined at MR cholangiography, the lesions lacked communication with the biliary tree. At histopathology, the mural nodule corresponded to an endocystic polypoid projection made of conjunctive septa. Three (27%) patients had associated focal nodular hyperplasia, and 1 (9%) had concomitant cholangiocarcinoma. MRI features allowed diagnosis of MBH with accuracy. Their recognition, especially the mural nodule, may help avoid misdiagnosis.