Well-differentiated tumors may be confused with complex hyperplasia with atypia histologically. Likewise, poorly differentiated tumors might be confused with sarcomas histologically. The differentiation of endometrial cancers is one of the most important prognostic factors. Subsequently, the depth of myometrial invasion and presence of tumor in the lymph nodes is directly related to recurrence rates and 5-year survival. As described in the introduction, there are other histologic variants of endometrial carcinoma.
Some tumors have more than one histologic variant.
These tumors are adenosquamous carcinomas. When corrected for grade, however, the presence of squamous components has not demonstrated a significant difference in prognosis when compared to pure adenocarcinomas. It is characterized by a higher incidence of deep myometrial invasion, lymph-vascular space involvement, lymph node metastases, extrauterine disease, and positive peritoneal cytology and implants. UPSC resembles papillary serous carcinoma of the ovary histologically. Unfortunately, UPSC does not share the same response to cytotoxic agents as does its ovarian counterpart.