<prompt> All of the following ovarian tumours usually occur bilaterally. Except -Metastatic massDysgerminomaAdenoma of ovaryDermoid cyst  <response>: Ans. is b d Dysgerminoma more than Dermoid cyst Ref Shaws, 13e, p 361 12e, p 317.Two option b d seem to be correct in this question b is the better option to go with.About dysgerminoma Shaws states It is usually unilateral.About dermoid cyst Shaw states that Dermoid cyst is bilateral in 10-15 cases. Ovarian adenomas are bilateral in 50 cases and.Metastasis to ovary is always bilateral. 