Immunoperoxidase investigation of Regan isoenzyme of alkaline phosphatase in maxillary sinus carcinomas.

The Regan isoenzyme of alkaline phosphatase is known to be produced ectopically by various malignant tumors. To assess whether this isoenzyme is expressed in maxillary sinus carcinomas, immunostaining for Regan isoenzyme was carried out on 35 maxillary sinus carcinomas comprising 27 squamous cell carcinomas, 6 adenocarcinomas, and 2 adenoid cystic carcinomas. The enzyme was shown to be present in 11 of 27 cases of squamous cell carcinoma, 2 of 6 cases of adenocarcinoma, and 1 of 2 cases of adenoid cystic carcinoma. Regan isoenzyme was identified in the cytoplasm and/or cell membrane of squamous cell carcinoma cells, whereas it was demonstrated mainly on the luminal membrane and in the secretions of both adenocarcinoma and adenoid cystic carcinoma cells. These findings show that Regan isoenzyme does, indeed, occur in maxillary sinus carcinomas.