MUC5AC and endocervical adenocarcinoma: In addition, HPV-associated mucinous-type endocervical adenocarcinomas can be misdiagnosed as endometrioid adenocarcinoma of the endometrium with extensive mucinous differentiation, and an algorithm for diagnosis has been proposed for tumors with abundant intracytoplasmic mucin using HPV testing and ER immunohistochemistry 13.