MUC5AC and extramammary Paget disease: Some previous studies observed that MUC5AC expression tended to be significantly higher in invasive lesions and metastatic lymph nodes than that in in situ lesions, which could be used as a marker for identifying high-risk EMPD (19–21), However, we found that MUC5AC lost in invasive pEMPD, which suggested that MUC5AC played a protective role; the decreases may promote tumor malignant potential.