Both CK7- and MUC5AC-reactive epithelia were significantly more frequent in non-neoplastic mucosae of CrD-SBC cases, in comparison with those of no-PID-SBCs (70% versus 19%, p<0.001, for CK7, and 59% versus 21%, p<0.001 for MUC5AC). The gene discussed is MUC5AC; the disease is pelvic inflammatory disease.