Intraductal spread of esophageal squamous cell carcinoma.

In order to determine the pathways of tumor dissemination in esophageal carcinoma, 175 lesions of squamous cell carcinoma of the esophagus were studied histopathologically and by electron microscope in relation to the intraepithelial spread and involvement of the esophageal glands by the carcinoma. The study compared vessel invasion and lymph node metastasis. Intraepithelial spread was seen in 111 lesions (63%) and gland duct involvement in 33 lesions (19%). Gland duct involvement was observed in 30% of the lesions positive for intraepithelial spread. In the intramucosal carcinomas, gland duct involvement was observed in 24%. Even in a very small carcinoma 7 X 5 mm in size, ductal spread was detected. This carcinoma did not reach the submucosa through stromal invasion. Patients with intramucosal carcinoma showed low incidence (20%) of lymphatic and/or blood vessel invasion and no incidence of lymph node metastasis. Examination by electron microscope showed that the cancer cells of the intraepithelial spread entered the duct by raising the normal ductal epithelium in the ductal cavity although the basal lamina was retained. Normal gland duct cells and cancer cells were either attached with desmosomes directly or were separated by degenerated epithelial cells. A high incidence of ductal involvement of the esophageal glands was seen in squamous cell carcinoma of the esophagus, indicating its possible importance as a route to the deep tissue in the early stage of this carcinoma.