Fibrous pseudocapsule of metastatic liver tumors from colorectal carcinoma. Clinicopathologic study of 152 first resection cases

Background: The presence of pseudocapsules of liver tumors has been recognized in hepatocellular carcinoma and is known to be a favorable prognostic factor. Although several studies have reported pseudocapsules around metastatic liver tumors, to the authors' knowledge there have been few evaluations of the clinical significance of such features in patients with metastatic colorectal carcinoma.

Methods: A clinicopathologic study was conducted in 152 patients who underwent initial hepatic resection for metastatic colorectal carcinoma.

Results: The presence of fibrous tissue between the tumor and the surrounding hepatic parenchyma was noted in 93 of the 152 patients (61%) with colorectal liver metastases. These patients were classified as having a thin pseudocapsule (n = 46) or a thick pseudocapsule (n = 47), according to the number of collagen bundles (< 10 or >/= 10) between the tumor and the hepatic parenchyma in histologic sections. Pathologically, the presence and thickness of the fibrous pseudocapsule were related closely to less invasiveness into adjacent vessels (P = 0.004) and the presence of macroscopic intrabile ductal invasion (P = 0.008). The postresection survival was significantly better in patients with thick or thin pseudocapsules than in those without a pseudocapsule (3-year and 5- year cumulative survival rates of patients with no, thin, and thick pseudocapsules were 41% and 31%, respectively, 71% and 64%, respectively, and 88% and 88%, respectively; P < 0.001). In a multivariate analysis using the Cox proportional hazards model, after adjusting for other potential prognostic factors (vascular invasion, bile ductal invasion, number of tumors, tumor size, and curativeness of surgery), the presence of a fibrous pseudocapsule was an independent predictor of a favorable outcome after hepatic resection.

Conclusions: The presence of fibrous tissue between the tumor and the liver parenchyma was a promising indicator of a better prognosis after resection in patients with colorectal liver metastases.