Bile duct adenomas consist of a proliferation of well-formed ducts in a background of fibrous stroma. Usually, the lymphocytes aggregate at the edge of the adenoma, but a moderate moderate amount of inflammation in the stroma is normal, as seen here.

The tubules are composed of plump, cuboidal epithelial cells. Fibrous stroma with inflammatory cells course between the tubules.

Bile duct adenomas are benign lesions usually found incidentally on autopsies or resected livers for other pathology. Some authorities believe this is not a neoplasm (clonal proliferation), but a hamaratoma (disorganized proliferation of mature elements normally present in the native tissue) of bile ducts. Either way, the entity is innocuous.

Bile duct adenomas and the classically described bile duct hamartomas (also known as bile duct malformations or von Meyenburg complexes) are very similar. Both tend to be found as circumscribed nodular lesions just under the liver capsule. However, bile duct hamaratomas have dilated bile ducts lined by an attenuated epithelium; there are also variable amounts of secretions (often inspissated bile) in their lumens. In contrast, bile duct adenomas have rounded, small uniform glands lined by plump cuboidal cells (Scheuer).

Bile duct adenomas often have aggregates of lymphocytes at the junction of the adenoma and normal liver.

Occurs in all ages, but most commonly found in middle-aged adults. There is no clear sex predilection.

None necessary.

Excellent. Lesion is completely benign.

For the pathologist, it is important to recognize the key features of bile duct adenomas and bile duct hamartomas (von Meyenburg complexes) since they appear as white nodules on the liver. Surgeons may send biopsies for frozen section to rule out metastases.

• Liver : Focal Nodular Hyperplasia

• Liver : Hepatic Hemangioma