The association of microcystic, elongated, and fragmented (MELF) invasion pattern in endometrial carcinomas with prognostic factors

Purpose: One of the most important prognostic factors for endometrial carcinoma (EC) is myometrial invasion. Microcystic, elongated, and fragmented (MELF) myometrial invasion (MI) pattern is also important in terms of diversity of the invasion. To the best the present authors’ knowledge, there is limited data about the significance of MELF type MI pattern, and lymph node (LN) involvement and therefore, the authors aimed to evaluate the frequency and association of MELF invasion pattern with other known prognostic factors in patients with EC. Materials and Methods: The authors reviewed the records of 102 patients who underwent staging surgery and had a result of EC in postoperative pathology in the present university clinic. Tissue specimens were re-evaluated according MI pattern (MELF positive or negative) by the same pathologist and the relation between the MELF pattern invasion and other prognostic factors were evaluated. Results: Stage Ia, Ib, II, IIIa, IIIb, and IIIc were observed 48 (47%), 29 (28%), 7 (7%), 11(11%), 1 (1%), and 6 (6%) in patients with EC respectively. Of the patients, MELF MI pattern was observed in 28 (27%) patients. When stage, grade, and MI patterns were compared, higher stage and grade were more frequently detected in patients with MELF pattern of MI. (p < 0.001) Moreover, none of the patients with grade 1 EC presented a MELF pattern MI. Patients with positive MELF MI pattern presented more lymphovascular space invasion (LVSI) (p < 0.001), LN metastasis (p < 0.05), and deeper MI (p < 0.001). Conclusion: Patients with MELF pattern of MI have more common LVSI and LN involvement.

Endometrial carcinoma; MELF; Myometrial invasion; Lymph node involvement

[1] Todo Y, Kato H, Kaneuchi M, Watari H, Takeda M, Sakuragi N. Survival effect of para-aortic lymphadenectomy in endometrial cancer (SEPAL study): a retrospective cohort analysis”. Lancet. 2010, 375, 1165.

[2] Mariani A., Dowdy S.C., Cliby W.A., Gostout B.S., Jones M.B., Wilson T.O., et al.: “Prospective assessment of lymphatic dissemination in endometrial cancer: a paradigm shift in surgical staging”. Gynecol. Oncol., 2008, 109, 11.

[3] Lopes L., Nicolau S., Baracat F., Baracat E., Goncalves W.J., Santos H., et al.: “Sentinel lymph node in endometrial cancer”. Int. J. Gynecol. Cancer, 2007, 17, 1113.

[4] Murray S.K., Young R.H., Scully R.E.: Unusual epithelial and stromal changes in myoinvasive endometrioid adenocarcinoma: a study of their frequency, associated diagnostic problems, and prognostic significance”. Int. J. Gynecol. Pathol., 2003, 22, 324.

[5] Quick C.M., May T., Horowitz N.S., Nucci M.R.: “Low-grade, low-stage endometrioid endometrial adenocarcinoma: a clinicopathologic analysis of 324 cases focusing on frequency and pattern of myoinvasion”. Int. J. Gynecol. Pathol., 2012, 31, 337.

[6] Stewart C.J., Brennan B.A., Leung Y.C., Little L.: “MELF pattern invasion in endometrial carcinoma: association with low grade, myoinvasive endometrioid tumours, focal mucinous differentiation and vascular invasion”. Pathology, 2009, 41, 454.

[7] Hertel J.D., Huettner P.C., Pfeifer J.D.: “Lymphovascular space invasion in microcystic elongated and fragmented (MELF)-pattern well- differentiated endometrioid adenocarcinoma is associated with a higher rate of lymph node metastasis”. Int. J. Gynecol. Pathol., 2014, 33, 127.

[8] Pavlakis K., Messini I., Vrekoussis T., Panoskaltsis T., Chrysanthakis D., Yiannou P., et al.: “MELF invasion in endometrial cancer as a risk factor for lymph node metastasis”. Histopathology, 2011, 58, 966.

[9] Mutch D.G.: “The new FIGO staging system for cancers of the vulva, cervix, endometrium and sarcomas”. Gynecol. Oncol., 2009, 115, 325.

[10] Nofech-Mozes S., Ackerman I., Ghorab Z., Ismiil N., Thomas G., Covens A., et al.: “Lymphovascular invasion is a significant predictor for distant recurrence in patients with early-stage endometrial endometrioid adenocarcinoma”. Am. J. Clin. Pathol., 2008, 129, 912.

[11] Guntupalli S.R., Zighelboim I., Kizer N.T., Zhang Q., Powell M.A., Thaker P.H., et al.: “Lymphovascular space invasion is an independent risk factor for nodal disease and poor outcomes in endometrioid endometrial cancer”. Gynecol. Oncol., 2012, 124, 31.

[12] Cole A.J., Quick C.M.: “Patterns of myoinvasion in endometrial adenocarcinoma: recognition and implications”. Adv. Anat. Pathol., 2013, 20, 141.