Diagnosis: Endometrial Adenocarcinoma
• The histologic grade of endometrial carcinoma is an important predictor of both the depth of myometrial invasion of the tumor and the likelihood of regional lymph node metastasis. Grade 3 adenocarcinomas are much more likely than grade 1 adenocarcinomas to demonstrate deep invasion of the myometrium and paraaortic and pelvic lymph node metastases.
• The histologic grading system of usual endometrial carcinomas is as follows: Grade 1 tumors demonstrate less than 5% solid (nonsquamous) component. Grade 2 tumors demonstrate 5% to 50% solid component. Grade 3 tumors demonstrate greater than 50% solid component. Grade 1 and grade 2 tumors with nuclear atypia inappropriate for the architectural grade are upgraded by one grade.
• Although the grade of the adenocarcinoma assigned at the time of biopsy often determines the surgical planning of the patient, the grade of the tumor may change at the time of the definitive surgery because of sampling error. This possibility increases the importance of intraoperative consultations in determining the next step for the patient.
• The concordance rate for high-grade carcinomas is significantly higher compared with well-differentiated carcinomas.
• Some endometrial carcinomas are selected out of the histologic grading system, mainly owing to prognosis. Serous carcinomas and clear cell carcinomas of the uterus are high grade by definition because of the poor prognosis associated with them. Secretory carcinoma is a low-grade carcinoma with an excellent clinical outcome. This tumor is also selected out of the grading system and is by definition grade 1.
