Uterus, endometrioid carcinoma

Endometrioid adenocarcinoma is the most common malignancy of the uterine endometrium. It typically occurs in perimenopausal and postmenopausal women, with an incidence of approximately 10-20 per 100,000 women. Tumours with abundant glandular growth (>90%) are considered more prognostically favourable (Grade 1); however, some cases demonstrate a microcystic, elongated, and fragmented glandular invasion pattern (“MELF”). The MELF pattern is uncommon but is associated with poor prognosis even in tumours that are Grade 1. In this case, the slide shows nests of Grade 1 endometrioid carcinoma extending deep into the myometrium, along with very focal lymphovascular invasion.