The infrequent case of three synchronous tumors (clear-cell ovarian carcinoma, uterine endometrioid adenocarcinoma, and adenosquamous cervical carcinoma) developed in organs evolving from the same germ layer, adjoined to the immunohistochemical overexpression of p53 with positive reaction in over 80% of the tumoral nuclei, demonstrates the uttermost importance of immunohistochemical technique involvement as a means to achieve a rigorous diagnostic approach. The gene discussed is TP53; the disease is endometrioid adenocarcinoma.