Introduction/Background Dedifferentiated endometroid adenocarcinoma (DEAC) was first described in 2007. However, it has only been recognised as a distinct subtype of endometroid adenocarcinoma in the last 1–2 years. As the diagnosis of DEAC is made based on the presence of any proportion of undifferentiated carcinoma component in coexistence with an endometrioid carcinoma component (usually low grade; i.e grade 1 or 2 endometrioid carcinoma), DEAC can sometimes be misdiagnosed as FIGO grade 2 or 3 endometrioid carcinoma.Distinguishing DEAC from poorly differentiated endometroid adenocarcinoma is important as the former carries a worse prognosis.

Methodology The study is a retrospective review of all cases of dedifferentiated endometrial cancer diagnosed in two institutions in Singapore between January 2012 and October 2017.

Results 7 patients were diagnosed with DEAC between April 2013 and October 2017. The mean age was 56.4 years. All patients presented with either abnormal uterine bleeding or post menopausal bleeding. Out of the 7 patients, one was diagnosed with Stage 2 disease, 5 were diagnosed with Stage 3 disease and 1 was diagnosed with Stage 4 disease. The 2-year overall survival (OS) was 31.3%, compared to 82.8% in patients with Grade 3 endometriod adenocarcinoma treated in the same centre. One patient had neoadjuvant chemotherapy, followed by surgery, and completion chemotherapy post surgery. The other 6 patients (87.5%) underwent primary debulking surgery. Out of these 6 patients, 5 patients had adjuvant chemotherapy post surgery and one patient had both adjuvant chemotherapy and radiotherapy. Lymphovascular invasion was found in 71.4% of the cases.

Conclusion DEAC is a more aggressive histological subtype. Patients with DEAC tend to present with advanced disease compared the other endometroid adenocarcinomas. Better awareness of this condition can lead to proper diagnosis. More research is needed on this rare histology subtype of endometrial cancer in order to tailor better treatment.

Disclosure Nothing to disclose.