Esophageal squamous cell carcinoma occurring in the surface epithelium over a benign tumor.

The coexistence of a benign tumor and carcinoma in the same esophagus is uncommon, while the occurrence of carcinoma in the surface epithelium over a benign tumor is considered to be extremely rare. Among 587 patients with surgically resected esophageal cancer, the cases with carcinoma located over a benign tumor of the esophagus were histopathologically investigated and the carcinogenesis of such cases was discussed. Only three cases were found to have esophageal squamous cell carcinoma located over benign tumors (two were leiomyomas and one was a lipoma). All three benign tumors protruded to the esophageal surface, and the carcinoma was located just over such tumors without coexisting epithelial dysplasia. Moreover, the epithelium, except for portions around these tumors, was intact in all three cases. From these findings it was suggested that chronic stimulation of the epithelium covering the benign tumors might have induced the carcinoma.