Papillary thyroid carcinoma overexpresses fully and underglycosylated mucins together with native and sialylated simple mucin antigens and histo-blood group antigens

We studied the immunohistochemical expression of mucins (MUC1, underglycosy lated MUC1, MUC2, MUC5AC, and MUC6), simple mucin antigens (Tn, sialyl Tn, and T), and histo-blood group antigens (type 1-Lewis(a) and sialyl Lewis;(a ) type 2-Lewis(x) and sialyl Lewis(x)) in a series of 26 papillary thyroid carcinomas (PTC), 6 follicular carcinomas, and a control group of 32 cases of "normal" thyroid parenchyma adjacent to the tumors. PTC expressed more o ften, more intensively, and more extensively every antigen but MUC6, which was not observed in any case. The expression of MUC5AC was also extremely r are. MUC1 expression was related to the expression of underglycosylated MUC 1, MUC2, Lewis,(a) and sialyl Lewis.(a) A trend toward an association betwe en the expression of MUC1 and that of type 2 histo-blood group antigens was also observed. Whenever there was a dissociation between the expression of type 1 and type 2 Lewis antigens, MUC1 appeared closely related to type 1 and independent from type 2 histo-blood group antigens. We conclude that MU C1 plays a pivotal, though not exclusive, role in the glycosylation feature s of well differentiated thyroid carcinomas. Despite the prominent expressi on of mucins and carbohydrate antigens in PTC, no significant differences w ere observed between PTC and follicular carcinoma thus ruling out the possi bility of using the aforementioned antigens as diagnostic markers per se.