The large cystic ovarian mass was suspicious for mucinous cystadenocarcinoma, given the non-cystic areas, the internal vasculature and the omental fat stranding. A bilateral salpingo-oophorectomy was performed and fortunately, pathology proved otherwise:

Macroscopic description:
Cystic mass weighing 3 Kg, measuring 24 x 18 x 12 cm. The mass contains turbid fluid, mucinotic, and consists of secondary cysts. Adjacent to the cyst there is a fallopian tube stump 2.5 cm long, with a 5-cm diameter.
Microscopic description:
Rt ovarian cystectomy:
Multilocular mucinous cystadenoma with foci showing borderline features.
Extensive necrosis and fresh hemorrhages are present.
The fallopian tube (rt part) shows no significant pathological changes.

Both fallopian tubes and the left ovary were without significant pathological changes.

The omentum showed areas of fresh hemorrhage, with no evidence of malignancy.