Significance of pericryptal fibroblasts in colorectal epithelial tumors: a special reference to the histologic features and growth patterns.

We analyzed the appearance of pericryptal fibroblasts (PCFs) identical to myofibroblasts in human colorectal epithelial tumors (adenomas, carcinomas) by an immunohistochemical method, with special reference to the histologic features and tumor growth patterns. The majority (61.5%) of adenomas contained well-developed PCFs. In contrast, carcinomas contained more poorly developed PCFs than adenomas. Approximately one third (35.4%) of the intramucosal and most (89.6%) of the submucosal carcinoma components had poorly developed PCFs. Pericryptal fibroblast development in pure carcinomas also was evaluated in association with two types of tumor growth patterns: polypoid growth carcinoma (PG-Ca) and nonpolypoid growth carcinoma (NPG-Ca). Polypoid growth carcinoma tended to contain well-developed PCFs, whereas NPG-Ca tended to lack PCFs. From the above findings, it is suggested that PCFs gradually decrease in the sequence of adenoma, intramucosal carcinoma, and submucosal invasive carcinoma. In addition, the two growth types (PG-Ca and NPG-Ca) are histologically different in PCF development, and the lack of a PCF network in NPG-Ca seems to be the reason why NPG-Ca can invade the submucosa more easily than PG-Ca, which has a consistent PCF network.