Fifty-eight surgically resected cases of intrahepatic cholangiocarcinoma (ICC) were examined grossly and microscopically. We microscopically categorized the ICC into two groups, "scirrhous-type" ICC (SICC) and "nonscirrhous-type" ICC (NSICC), according to the degree of the stromal desmoplasia in the tumor. We next assessed the histologic characteristics including proliferative activities and prognoses. Additionally, the prognostic factors of ICC were examined by univariate and multivariate analyses. Histologically, the incidences of lymphatic permeation and perineural invasion in SICC (85.7% and 100.0%, respectively) were significantly higher than those in NSICC (47.7% and 45.6%, respectively). The mean MIB-1 labeling index of SICC (mean +/- standard deviation, 29.9% +/- 14.3%) was significantly higher than that of NSICC (mean +/- standard deviation, 19.1% +/- 14.3%). Additionally, the 1- and 3-year survival rates of the SICC were 64.3% and 22.0%, respectively, and those of NSICC were 72.8% and 55.8%, respectively. The survival rate of SICC was significantly lower than that of NSICC. Overall, lymphatic permeation, intrahepatic metastasis, and lymph node metastasis were all considered to be independent prognostic factors for a worse prognosis based on the multivariate analyses, whereas our new category based on stromal desmoplasia or other variables were not. Our study thus indicates that lymphatic permeation, perineural invasion, and a higher proliferative activity of tumor cells carry a poorer prognosis in SICCs than in NSICCs. Although the overall independent prognostic factors were lymphatic permeation, intrahepatic permeation, and lymph node metastasis based on a multivariate analysis, a detailed histologic examination related to the stromal desmoplasia in the tumor is also considered to be useful for evaluating the biologic behavior of the TCC.
