Case Report
Copyright ©2009 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Oct 21, 2009; 15(39): 4976-4979
Published online Oct 21, 2009. doi: 10.3748/wjg.15.4976
Muscularis mucosae in desmoplastic stroma formation of early invasive rectal adenocarcinoma
Shinichi Ban, Michio Shimizu
Shinichi Ban, Department of Pathology, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi, Saitama 332-8558, Japan
Michio Shimizu, Department of Pathology, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka, Saitama 350-1298, Japan
Author contributions: Ban S performed the work and wrote the manuscript; Shimizu M supervised the work.
Correspondence to: Shinichi Ban, MD, Department of Pathology, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi, Saitama 332-8558, Japan. shinba@saiseikai.gr.jp
Telephone: +81-48-2538562 Fax: +81-48-2538562
Received: July 14, 2009
Revised: September 7, 2009
Accepted: September 14, 2009
Published online: October 21, 2009
Abstract

The origin of myofibroblasts or myofibroblastic cells in the desmoplastic stroma associated with carcinoma invasion has been controversial. In the early invasive area of a rectal adenocarcinoma reported here, an obvious transition between the muscularis mucosa and the bundles of eosinophilic stromal cells observed in the carcinomatous stroma was demonstrated both in morphology and in their cytoskeletal phenotype, which conceivably suggests that the smooth muscle cells of the muscularis mucosa could convert to the eosinophilic stromal cells, namely myofibroblasts. Moreover, type I procollagen was demonstrated in both protein and mRNA levels in the areas of eosinophilic stromal cells with a lesser degree of differentiated smooth muscle phenotype that showed a transition from the muscularis mucosa, implying that the myofibroblastic cells converted from smooth muscle cells of the muscularis mucosa could be responsible for type I collagen production. These findings suggest that the muscularis mucosae may not be a passive barrier through which colorectal carcinomas infiltrate into the submucosa, but may play an active role in the formation and remodeling of tumor stroma.

Keywords: Rectal adenocarcinoma; Muscularis mucosa; Myofibroblast; Cytoskeletal phenotype; Type I collagen