<prompt> True about dermoid cyst of ovary :It is teratomaFrequently undergo torsionX-ray is diagnosticAll  <response>: Ans. is a. b, and c i.e. It is teratoma; Frequently undergo torsion; X-ray is diagnostic; and Contains sebaceous material and hairs Dermoid cyst mature teratoma : Most comon benign ovarian neoplasm. Mostly affect women of reproductive age group. Morphologically dermoid cyst is unilocular with smooth surface. On cross section -- cysts are unilocular and typically contain are area of localised growth that prottectes into the cystic cavity called as Rokintansky protuberance dermoid process. It contains sebaceous material and hair with teeth. bone, cailage, thyroid tissue. If teeth or bone are seen in X-ray in adnexal mass, this finding is pathognomic for teratoma. Dermoid cyst are bilateral in 12 to 15 and frequently arise in association with mucinous cystadenomas. Malignant change in a dermoid cyst occurs in 0.5 -- 2 cases in patients 40 years. Most common malignancy which develop is. squamous cell carcinoma. 