Abstract: Objective To investigate the clinical pathological and immunophenotypic characteristics of endometrial carcinoma with microcystic, elongated, and fragmented growth patterns (MELF). Methods The clinical and pathological data of 72 cases of patients with endometrioid carcinoma who underwent hysterectomy, bilateral adnexectomy, and pelvic lymph node dissection at Bazhou People's Hospital in Xinjiang from September 2013 to January 2019 were collected, and were to determine the infiltration of MELF. The general information, clinical and pathological characteristics, immunohistochemical staining results of the patients were investigated and compared, and the prognosis of the patients were followed up. Results In the 72 patients, there were 12 cases (16.7%) were pathologically diagnosed as endometrial carcinoma with MELF growth pattern (with MELF infiltration group); There were 60 patients with endometrioid carcinoma without MELF growth pattern (without MELF infiltration group), accounted for 83.3% (60/72). There were no significant difference in body mass index, educational years, etc. compared between the group with MELF infiltration and the group without MELF infiltration (P>0.05), but there were significant difference in age and menopausal status compared between the two groups (P<0.05). There were significant differences in pathological grading, lymphatic vessel interstitial infiltration, and lymph node metastasis compared between the group with MELF infiltration and the group without MELF infiltration (P<0.05). In the group with MELF infiltration, the positive expression rates of ER, PR, Ki-67, P16, and CK were 8.3%, 16.7%, respectively 91.6%, 100.0%, and 100.0%. In the group with MELF infiltration, ER, PR, Ki-67, P16, and CK showed strong brown yellow positive expression, with the positive expression rate of 100.0%. During the follow-up period, patients did not experience any tumor metastasis or recurrence. Conclusion MELF infiltration is a special infiltration pattern that occurs in low-grade endometrial carcinoma. Patients with MELF growth pattern in endometrial carcinoma have a significantly higher LVSI positive rate and lymph node metastasis positive rate, the positive rates of ER and PR expression were significantly reduced.

Key words: endometrioid carcinoma, immunohistochemistry, pathological characteristics, microcystic, elongation, fragmented