Acombinedhistopathological,mucinhistochemi-calandimmunohistochemicalstudyofthetransitionalmucosa(TM)adjacenttocolorectalcancerispresented.Twenty-sixresectedspecimenswerestudiedbyhematoxylinandeosin(HE)andhighirondiamine-alcianblue(HID-AB).Carcinoem-bryonicantigen(CEA)wasdemonstratedbyperoxi-daseantiperoxidass(PAP)technique.TheappearanceoftheTMisusuallythicker,longeranddilatedcryptswithincreasedimmatureandintermediatecells.VariableamountofsialomucinsanddecreasesulphomucinscontentaswellasincreasedCEAcontentarefoundintheTM.Thesechangesarenotseeninnon-transitionalzoneandnormalcolorectalmucosa.ItissuggestedthatthemucinchangesandexpressionofCEAintheTMmayindicateanearlyprimarypremalignantchangesandmaybeoneofthereasonsfortheTMaffectingtheprognosisofpatientswithlargebowelcancerafterradicalresection.
