A histochemical study revealed focal intracytoplasmic
mucin within 50% of a series of
adenocarcinomas arising within the endometrium. Seventeen percent of the
adenocarcinomas studied contained intracytoplasmic O-acetylated
sialomucins, as demonstrated by the PB/KOH/PAS technique. The presence of O-acetylated
sialomucin, indicating enteric or intestinal differentiation, has not previously been demonstrated within endometrial
adenocarcinomas, although it is well described in endocervical
adenocarcinomas and in mucinous
tumors of the ovary. In none of the cases in which enteric-type
mucins were identified was there morphological evidence of intestinal differentiation in the form of goblet cells or Paneth cells. No correlation was found between the presence of enteric
mucins and the grade of the
adenocarcinoma. The results of the study provide further confirmation of the ability of the epithelial lining of the female genital tract to undergo various forms of
metaplasia, along both Mullerian and non-Mullerian pathways. The demonstration of specific
mucins is more sensitive than morphology in establishing enteric differentiation.