Fibrous tumor-liver interface in large hepatic neoplasms: its significance for tumor resection and enucleation.

Based on the clinical observation that large tumors located in the liver may be resected or enucleated with relative ease, the present retrospective study aimed at the detailed assessment of the tumor/liver interface in large hepatic neoplasms. For this purpose, a systematic light microscopic and immunohistochemical study on resection specimens of 10 giant hemangiomas, 10 hepatocellular carcinomas, and 9 liver metastases was performed. In giant hemangiomas, four distinct interface patterns were identified: fibrous interface (pattern A), interdigitating interface (pattern B), compression interface (pattern C), and irregular/spongy interface (pattern D). In 5 of 10 of these tumors, a single interface type (pattern A) was observed, whereas the other five tumors exhibited a mixed interface type, although two of them had a predominance of pattern A. Overall, 7 of 10 giant hemangiomas were exclusively or partially separated from liver substance by a distinct fibrous interface. Similarly, a fibrous interface of variable thickness and containing remnants of preexisting portal tracts was observed in 18 of 19 malignant epithelial tumors, and in 10 of 18 tumors, this fibrous zone was complete, ie, totally covering the tumor border facing the resection surface. These findings indicate that large hepatic tumors, both benign and malignant, can induce a distinct fibrous interface in a large proportion of cases. We suggest that such an interface, grossly visible as a capsulelike structure, plays a significant role for the resectability of large liver tumors.