Pathologic Staging of Endometrial Carcinomas: Selected Areas of Difficulty.

Accurate staging of cancers is an important determinant of prognosis and guides optimal patient treatment. Although the International Collaboration on Cancer Reporting recommends that endometrial cancers (including carcinosarcomas) are pathologically staged using the International Federation of Gynecology and Obstetrics (FIGO) 2009 system, in many areas TNM [American Joint Committee on Cancer (AJCC) or Union for International Cancer Control (UICC)] staging is used or even mandated; these latter systems are based on FIGO 2009. In this review, areas of difficulty in the pathologic staging of endometrial carcinomas are covered with practical advice for the reporting pathologist. These include issues regarding the assessment of the depth of myometrial involvement (which may be rendered difficult due to a variety of factors), tumor involvement of adenomyosis, and assessment of cervical and uterine serosal involvement. Although not included in the FIGO staging system, the issue of lymphovascular space invasion (LVSI) is covered as this is of prognostic importance and there are multiple problems in the pathologic assessment of this. One important point is that tumors should not be upstaged based on the presence of LVSI alone without tissue involvement; for example, the presence of LVSI in the outer half of the myometrium or in cervical or adnexal vessels in a carcinoma with myoinvasion confined to the inner half of the myometrium is still FIGO stage IA. The issue of simultaneously occurring tumors of the endometrium and adnexa is also covered with advice on how to distinguish between synchronous independent and metastatic neoplasms of both endometrioid and nonendometrioid types. Recent molecular evidence showing that simultaneously occurring endometrioid carcinomas of the endometrium and ovary are clonal and thus probably represent metastatic disease from the endometrium to the ovary rather than synchronous independent neoplasms, as is widely assumed, is discussed.