PTEN and carcinosarcoma: Whereas, uterine papillary serous carcinomas are typically associated with p53 mutations and often Her-2/neu mutations, with PTEN mutations being rare, carcinosarcomas, characterized by both malignant epithelial and mesenchymal components, are associated with many of the epidemiological risk factors linked to endometrioid carcinomas including obesity and tamoxifen therapy, which suggests that dysregulated estrogen signaling may have a role in its pathogenesis and may represent a therapeutic target.