HNF-1β was positive in 7/9 (78%) clear cell carcinoma, in 2/5 (40%) of usual type of endocervical adenocarcinoma, in 3/11 (27%) of gastric-type of endocervical adenocarcinoma, in 3/3 (100%) minimal deviation adenocarcinoma, in 1/1 (100%) mesonephric adenocarcinoma, in 1/1 (100%) serous adenocarcinoma, and in 1/1 (100%) malignant mixed Müllerian tumor. The gene discussed is HNF1B; the disease is carcinosarcoma.