Section II: pathology and pathologic staging of esophageal cancer.

Most benign and malignant neoplasms of the esophagus are epithelial in origin. Esophageal carcinomas typically show either glandular or squamous differentiation and arise through the progression of premalignant conditions: Barrett's esophagus for adenocarcinoma and squamous dysplasia for squamous cell carcinoma. Esophageal carcinomas are aggressive neoplasms that spread through the esophageal wall and metastasize to regional lymph nodes and distant organs. Early detection and treatment of these tumors is the most important factor in patient survival.