Multidirectional differentiation of endometrial carcinoma with special reference to tumor aggressiveness evaluated by Ki-67 expression

To clarify the correlation between multidirectional differentiation and agg ressiveness of endometrial adenocarcinomas, we assessed both proliferative activities (PA) using Ki-67 expression and squamous and/or endocrine differ entiation. We divided 51 adenocarcinomas into 22 adenocarcinomas with typic al squamous differentiation (greater than or equal to 10% of tumor cells, t ypical SQ) classified into 10 adenoacanthomas (AA) and 12 adenosquamous car cinomas (AS), 17 adenocarcinomas with focal squamous differentiation (<10% of tumor cells), and 12 typical adenocarcinomas without morphological squam ous differentiation (pure AC), according to the new WHO classification. Par affin-embedded sections were stained using monoclonal antibodies against hi gh-molecular-weight keratins (HMWK) to recognize squamous cells, chromogran in A to recognize endocrine cells, and Ki-67 antigen to recognize prolifera ting cells. Both AA and AS exhibited lower PA than pure AC. Typical SQ exhi bited lower PA than pure AC. This difference was also significant after sel ecting only grade 1 or stage I/II cases. AA exhibited lower PA than AS and also after selecting only grade 1 or stage I/II cases. PA of adenocarcinoma with the expression of HMWK in greater than or equal to 30% of tumor cells was lower than those without HMWK. PA of adenocarcinoma with the expressio n of chromogranin A in greater than or equal to 10% of tumor cells was lowe r than those without chromogranin A. These differences were also significan t after selecting only grade 1 or stage I/II cases. Squamous and/or endocri ne differentiation is a good marker for a reduction of PA. Endometrial aden ocarcinomas with multidirectional differentiation exhibited lower PA and we re likely to be more mature than those with monodirectional differentiation . (C) 1999 Academic Press.