Mesonephric Adenocarcinoma of the Uterine Corpus: A Report on 2 Cases With Comparison to Its Cervical Counterpart.

Mesonephric adenocarcinoma (MA) is a rare tumor of the female genital tract that develops in the uterine cervix. Recently, a few cases of MA arising from the uterine body have been reported, whereas the differences between these 2 entities remain unknown. Two uterine MAs and 1 cervical MA were included in this study. In uterine MA, there was an admixture of various growth patterns with tubular, glandular, slit-like, papillary, and solid architectures. Both tumors extensively involved the endometrium, while no mesonephric remnants were noted. Immunostaining was diffusely positive for TTF-1, while there was only focal staining for GATA3. KRAS somatic mutation was present in both uterine cases. In cervical MA, the tumor also had different growth patterns but no endocervical mucosa involvement. A residual mesonephric duct was present. GATA3 showed diffuse staining, but TTF-1 was totally negative. Therefore, uterine MA was not entirely consistent with its cervical counterpart in both morphologic characteristics and immunostaining.