Introduction/Background Ovarian cancer has the poorest prognosis among all gynaecological cancers and diagnosis is often late. It is imperative to fully understand the ultrasound features of ovarian masses as US is usually the first imaging modality in diagnosis.

In particular, the features of papillary projections can be challenging to describe on US and to differentiate between the different classes of ovarian masses.

Methodology This is a retrospective study from January 2009-December 2018. The histology of all cases that underwent a cystectomy or oophorectomy were analysed at Guy’s and St Thomas’ hospital. Those that had a histological diagnosis of papillary projections and had pre-operative US 2D images were included. The image was assessed to determine the presence of locules, solid components and irregular septations. If papillary projections were visualised on US, they were assessed for size, distribution, doppler presence, regularity and angle between cyst wall and papillary projection. This study was approved as a service improvement project.

Results In the 9-year period, 114 masses with papillary projections on histopathology were observed and the the median age of patients was 55, range (65–42).

Of the 114 tumours included 112 were epithelial tumours and 73/114 were malignant, 22/114 were borderline and 19/114 were benign. Ultrasound detected papillary projections in 93/114 ovarian masses. The mean size of papillary projections were 12.9, 16.5 and 22.8mm in benign, borderline and malignant masses respectively. Dissemination, doppler presence and irregularity of the surface of the papillary projection were all strongly associated with malignancy (Chi2 tests, P values of 0.0005, 0.0003 and 0.008 respectively). However, there was no significant difference between the angle in benign and malignant tumours.

Conclusion Morphological and doppler features of papillary projections are strongly associated with benign or malignant ovarian tumours. The angle of the papillary projection does not appear to aid this diagnosis.

Disclosures No disclosures.