Application of Mucin Histochemistry for Pathological Diagnosis

Using an array of histochemical and immunohistochemical techniques, we have characterized the various types of mucins in the normal, metaplastic and neoplastic stomach, pancreas and biliary ducts, in the normal and neoplastic esophagus, colon and lung, and in tumors of the ovary. Gastric phenotypes were variously expressed in metaplastic and neoplastic cells in these organs. Their expression was usually associated with an organoid differentiation simulating the gastric pyloric mucosa.In gastric intramucosal carcinoma tissues, neoplastic cells often proliferated forming structures resembling non-neoplastic gastric mucosa. Thus, carcinoma cells in the more superficial layers expressed strong galactose oxidase cold thioneine Schiff reactivity (a surface mucous cell type property), whereas cells in the deeper layers were stained by paradoxical concanavalin A staining (a glandular mucous cell type property). Proliferative cells were perferentially located in the middle layers. This organized differentiation is lost in portions of the tumor that have invaded beyond the muscularis mucosae. Adenocarcinoma cells in both the bile duct and the pancreatic duct, in the bronchioloalveolar carcinoma of the lung and in mucinous cyst adenoma of the ovary showed gastric phenotypes and organoid differentiation. In papillary portions of these tumors, cells in protruded portions of the neoplastic papillae tended to express phenotypes of surface mucous cell, while in the indented portions they expressed phenotypes of glandular mucous cell. The goblet cell metaplasia in areas adjacent to pancreatic ductal carcinoma is identical to gastric pyloric metaplasia.We conclude that the systematic use of mucin histochemistry, a relatively simple technique that can be implemented in most histopathology laboratories, may provide important information about structure and property of neoplastic tissues and could enhance our understanding of carcinogenesis in many organs.