What is the most common histologic type of endometrial cancer?

• A. Adenocarcinoma
• B. Squamous cell carcinoma
• C. Leiomyosarcoma
• D. Choriocarcinoma

Answer: (A)

The key idea is that endometrial cancers most commonly arise from the glandular lining of the uterus and are typically adenocarcinomas, specifically the endometrioid subtype. This histology forms gland-like structures that resemble normal endometrium, which is why adenocarcinoma best fits as the common pattern. Other tumor types listed originate from different tissues within the uterus or are much rarer in the endometrium—squamous cell carcinoma of the endometrium is uncommon, leiomyosarcoma comes from the myometrium (the smooth muscle layer), and choriocarcinoma is a trophoblastic tumor. Therefore, the gland-forming adenocarcinoma, especially the endometrioid type, is the most frequent histologic type.