They are the most common of all ovarian T. (70%). They arise from surface epithelium and subdivided into:
1) Serous Tumours:
They are subdivided into:
i. Simple serous cyst: solitary, unilocular, unilateral, containing serous fluid and no malignant potential.
ii. Serous papillary cystadenoma: extra or intracystic papillae,malignant potential in 30-50%
iii. Serous papillary cystadenocarcinoma
2) Mucinous Tumours:
Large, bilateral, multilocular and containg mucinous material. Rupture will lead to PSEUDOMYXOMA PERITONEI
3. Brenner's Tumour:
It is a benign, unilateral, small solid ovarian T. It is associated with MEIG'S SYNDROME, characterised by ascites, Rt pleural effusion and ovarian tumours (Brenner's, fibroma and theca cell tumour). PseudoMeig's syndrome is the same but with subserous fibroid instead of ovarian T.
4. Endometroid Tumour:
Tumour is formed of endometial-like tissue and endometrial carcinoma may arise on top of it.