[1398] Cystic Biliary Hamartoma of the Liver: 17 Examples of a Clinicopathologically Distinct Entity

I Coban, D Altinel, D Martin, B Kalb, J Sarmiento, NV Adsay. Emory Uni., Atlanta

Background: A hitherto unrecognized type of cystic lesion in the liver which appears to be the cystic/complicated version of bile duct hamartoma is described.
Design: Clinicopathologic features of 17 cases with a distinctive MRI appearance and corresponding pathologic findings were analyzed. Only the patients that underwent hepatic resection for this suspected lesion were included into the study.
Results: 12 female, 4 male. Mean age, 62 (40-84). Mean size, 11 cm (2-30). MRI: Distinctive and specific pattern characterized by a lobulated, well-marginated cyst demonstrating a very thin line of peripheral rim enhancement. MRI also showed multiple small bile duct hamartomas in the uninvolved hepatic parenchyma in 13/17. Gross: Cyst walls, well defined fibrotic band (0.1-0.8 cm). Cyst lining, smooth and devoid of any excresences or discrete lesions; however, substantial hemorrhage in 8, and purlent contents in 1 (with previous history of intervention). Fibrous septations, creating a pattern of multilocularity in 11. Microscopy: The cyst walls, composed predominantly of fibrous tissue containing biliary ductules and low to moderate inflammation. In 8, microscopic conglomerate of dilated ducts on the cyst walls with all the characteristics of bile duct hamartomas (von-Meyenburg complexes) including contour irregularities, attenuated epithelium, and 2 with bile in the lumen, many giving the impression of transforming into the main cyst. In 9, macroscopic daughter cysts with features of von- Meyenburg complexes. Cyst lining, often attenuated, and where preserved, low cuboidal with minimal cytoplasm, and exhibiting the typical appearance of bland biliary epithelial cells. Other findings variably present: hemorrhage in 8, calcification in 6, and vascular malformation in 3 (suggestive of a developmental ductal plate abnormality). Other lesions: bile duct hamartomas in 13 and hemangioma in 1. Uninvolved liver: steatosis in 6, cirrhosis in 1, and the remaining 10 unremarkable.
Conclusions: Described here is a previously uncharacterized type of cystic lesion in the liver with distinctive clinicopathologic features. The MRI findings and morphologic appearance are that of a mega-cystic version of bile duct hamartomas, and they are also frequently associated with smaller hamartomas in adjacent liver. Therefore, we propose the term cystic biliary hamartoma for this entity.
Category: Liver & Pancreas

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 247, Wednesday Morning