Proliferation of α-smooth muscle actin-containing stromal cells (myofibroblasts) in the lamina propria subjacent to intraepithelial carcinoma of the esophagus

Background: The lamina propria of the digestive tract is the space containing vessels, myofibroblasts, and other interstitial components. The present study was undertaken to elucidate the relationships between the proliferation of myofibroblasts within this space and other histological features such as inflammatory cell infiltration and proliferation of blood vessels. Methods: Thirty-eight cases in total-comprising 19 cases of early and 19 cases of advanced esophageal squamous cell carcinoma with intraepithelial extension (the former including 10 lesions of carcinoma in situ and 15 lesions of carcinoma with invasion only into the lamina propria)-were examined using H&E staining, Azan Mallory staining, and immunostaining for the characterization of mesenchymal cells in the lamina propria against alpha -smooth muscle actin (alpha SMA), desmin, vimentin, factor Vm, collagen type IV, laminin, or inflammatory cells (L26, UCHL1, Kp1, and c-kit). The proliferative potential of myofibroblasts was evaluated by measuring the total Length of the bundles of myofibroblasts per case. Results: proliferation of alpha SMA-containing stromal cells: i) occurred in the lamina propria subjacent either to intraepithelial carcinomas (64%) or to the intraepithelial extension of carcinoma tissue (47%), and ii) showed a significant correlation with both the degree of mononuclear cell infiltration (mostly UCHL1-positive T cells) and the total length of the carcinoma tissue in each case. Conclusions: Proliferation of alpha SMA-containing stromal cells in the lamina propria may be involved in altering the endoscopic features of the esophagus in cases with intraepithelial carcinoma or an intraepithelial extension of carcinoma tissue.