Comparison between colorectal low- and high-grade mucinous adenocarcinoma with MUC1 and MUC5AC

AIM:To explore useful prognostic factors for mucinous adenocarcinoma(MAC) in the colon and rectum.METHODS:MAC was divided into low-and high-grade types based on the degree of structural differentiation;low-grade MAC arisen from well to moderately differentiated adenocarcinoma and papillary carcinoma,and high-grade MAC from poorly differentiated adenocarcinoma and signet ring cell carcinoma.Immunohistochemically,the expression of 2 types of MUC1(MUC1/DF and MUC1/CORE),MUC2,2 types of MUC5AC(MUC5AC/CHL2 and HGM),MUC6,CDX2,and CD10 was examined in 16 cases of MAC consisting of 6 low-and 10 high-grade types.RESULTS:MUC1/DF3 was expressed in 3 of 6 low-grade MAC(50) and 10 of 10 high-grade MAC(100).MUC1/CORE was expressed in 1 of 6 lowgrade MAC(16.7) and 7 of 10 high-grade MAC(70).MUC2 was expressed in all MAC regardless of the grade.MUC5AC was expressed in 6 of 6 low-grade MAC(100) and 4 of 10 high-grade MAC(40).HGM was expressed in 5 of 6 low-grade MAC(83.3) and 6 of 10 high-grade MAC(60).Expression of MUC6 and CD10 was undetected in all MAC regardless of the grade.CDX2 was expressed in 5 of 6 low-grade MAC(83.3) and 7 of 10 high-grade MAC(70).Taken together,MUC1/DF3 was expressed significantly more frequently in high-grade MAC than in low-grade,and MUC5AC/CHL2 was expressed significantly more frequently in low-grade MAC than in high-grade.CONCLUSION:It is proposed that MUC1/DF3 and MUC5AC/CHL2 immunostaining is useful to discriminate high-grade MAC from low-grade MAC.