Correlation of myoinvasion patterns of endometrial endometrioid carcinoma with routine histopathologic, immunohistochemical and prognostic parameters

Aim: The aim of our study was to compare myoinvasion patterns with other histopathologic and immunohistochemical parameters as well as with recurrence, lymph node metastasis, distant metastasis and overall survival in cases of endometrioid carcinoma of the endometrium. In addition, it was aimed to compare the myoinvasion patterns with one another and to evaluate them with the data in the literature. Material and Methods: A total of 144 cases of endometrial endometrioid carcinoma were selected from hysterectomy materials in the archive of the Department of Medical Pathology, Manisa Celal Bayar University Faculty of Medicine. In addition to the expansile, diffusely infiltrating, MELF, adenomyosis-like and adenoma malignum type myoinvasion patterns described in the literature, classical histopathologic parameters were also evaluated. The findings were compared with other histopathologic and immunohistochemical parameters as well as with recurrence, lymph node metastasis, distant metastasis and overall survival. Results: When the myometrial invasion patterns were examined, it was observed that tumors with a expansile pattern were at an earlier stage (p<0,001) and had less cervical stromal involvement (p=0,02). It also showed less depth of myometrial invasion (p=0,04), less lymphovascular invasion (p=0,01) and lower Ki-67 proliferation index (p<0,001). These findings showed that tumors with expansile pattern had a good prognosis. Tumors with diffusely infiltrating pattern had higher histological grade (p=0,014), more advanced stage (p=0,002), more cervical stromal invasion (p=0,02) and LVI (p=0,03). Tumors with MELF pattern were shown to have deeper myometrial invasion (p=0,04) and were associated with lymphovascular invasion (p=0,04). However, no significant correlation was found between lymph node metastasis and MELF pattern in our study. 33,3 percent of cases with tumors having MELF pattern were found to be MSI tumors and no statistically significant relationship was found between them. Histological grade, tumor size, depth of myometrial invasion (also whether exceeding 1/2 of myometrium), cervical stromal involvement, lymph node metastasis and stage were statistically significant variables in the survival analysis. In addition, as far as myometrial invasion patterns were concerned, it was observed that tumors with expansile pattern had a better survival than tumors with diffusely infiltrating pattern (p=0,004). Tumors with diffusely infiltrating pattern had a 3,2-fold increased risk of death compared to tumors with expansile pattern (p=0,044). Conclusion: The prognostic value of myometrial invasion patterns in endometrioid carcinomas has recently been a subject of research and various studies have been conducted on this subject. In our study, we have shown that the expansile pattern was associated with better prognostic factors, the diffusely infiltrating pattern was associated with worse prognostic factors, and the MELF pattern was more associated with lymphovascular invasion. It seems that further and larger studies are needed to clearly define the relationship between myometrial invasion patterns and prognostic factors. Keywords: Endometrioid carcinoma, myometrial invasion patterns, expansile pattern, diffusely infiltrating pattern, MELF pattern.