We appreciate Dr Rutgers' interest in our recent article on müllerian mucinous borderline tumor (MMBT) [1].Dr Rutgers added another manuscript demonstrating differential immunophenotype between MMBT and intestinal mucinous borderline tumor (IMBT), using antibodies for CEA, MOv8, and CA19-9 [2]. This finding further substantiates the general conception that IMBT is histogenetically and clinicopathologically different from MMBT. In this context, the current World Health Organization classification...