Welcome to HCM.
Mass or cyst in the ovary could be benign or malignant. In most of the cases on ultrasound
we can confidently make a diagnosis whether it is malignant or benign, clear cyst or chocolate cyst
or dermoid cyst
But sometimes the findings are confusing and in these cases best alternative available is laparoscopic evalation of the mass.
I think you should get a laparoscopy
done, if not already done and if the cystic mas is persisting.
Wish you all the best.