Solid liver hamartoma, bile ductal fibroadenomatous type Report of a case

An unusual hepatic hamartoma developing in a 15 month-old female with abdominal distension of three month's duration was described. From the age of patient, high titer of serum α-fetoprotein and findings of computerized tomography and angiography of the lesion, hepatoblastoma was highly suspected, The oval, elastic hard and pedunculated lesion (900g, 14.5×13×7cm) arose in the anterior edge of left heaptic lobe, without adhesion. On cut-surface, the sharply demarcated, solid lesion was composed of irregular shaped islands of parenchyma and various sized nodules of fibrous stroma, intermingled with each other in a mozaic pattern. Histologically, the stroma included prominent bile ductal proliferation with periductal thickcollagenous bundles and angiomatous vascular proliferation with loose connective tissue, and it showed a similar feature to the intracanalicular type of mammary fibroadenoma. Islands of the differentiated parenchyma were pared off by the proliferating stroma. Immunohistologically, α-fetoprotein was demonstrated in the parenchymal cells of the lesion. It is reasonable to consider from these findings that the lesion is undoutedly a hamartoma and its essential change is fibroadenomatous proliferation of the bile duct. We propose here therfore, to call this solid hepatic lesion "bile ductal fibroadenomatous hamartoma".