Abnormal expression of p53 and p16 is a high-risk marker in endometrial cancer, particularly for diagnosing aggressive uterine serous carcinoma. Which tumor type is most associated with this finding?

• A. Uterine serous carcinoma
• B. Endometrioid adenocarcinoma
• C. Clear cell carcinoma
• D. Leiomyosarcoma

Answer: (A)

The key idea is that abnormal p53 expression paired with altered p16 marks a highly aggressive endometrial tumor type. In endometrial cancer, p53 mutations are a hallmark of serous carcinomas, which behave much more aggressively than other endometrial cancer subtypes. Immunohistochemically, these tumors often show a mutant p53 pattern—either diffuse strong nuclear staining or complete absence—and there is frequently accompanying dysregulation of p16, reflecting disturbed cell-cycle control. This combination is especially characteristic of uterine serous carcinoma, making it the best-supported association for this high-risk marker pattern.

Other endometrial tumor types tend to have different molecular profiles: endometrioid adenocarcinoma more commonly features alterations like PTEN or beta-catenin mutations and does not rely on the same p53/p16 signature; clear cell carcinoma can show various molecular changes but the distinctive p53/p16 pattern linked to aggressive serous behavior is less defining; leiomyosarcoma is a mesenchymal tumor with different markers and molecular pathways.