DiVerential expression of high molecular weight caldesmon in colorectal pericryptal fibroblasts and tumour stroma

Aim—To investigate an extent of smooth muscle diVerentiation of pericryptal fibroblasts. Methods—Expression of high molecular weight caldesmon (h-CD) and á smooth muscle actin was investigated in 123 invasive colorectal adenocarcinomas and their surrounding non-neoplastic tissues. Results—The monoclonal antibody to h-CD, which showed predominantly positive immunostaining in well diVerentiated smooth muscle cells, recognised pericryptal fibroblasts, smooth muscle cells, and pericytes, but was not reactive to myofibroblasts. Antibody to á smooth muscle actin recognised not only pericryptal fibroblasts, smooth muscle cells, and pericytes but also myofibroblasts. Conclusions—Pericryptal fibroblasts show greater smooth muscle diVerentiation than myofibroblasts and there is a possibility that they are well diVerentiated smooth muscle cells; h-CD is an excellent marker to discriminate pericryptal fibroblasts from myofibroblasts. (J Clin Pathol 1999;52:785–786)