A rare case of collision tumour of the ovary complicated by torsion.

Collision tumour is the coexistence of two adjacent, but histologically distinct tumours without histologic admixture. Collision tumours are rare in the ovary. It is mostly a histopathological diagnosis often missed in preoperative imaging. The radiologist, gynaecologists and pathologists should be aware of such a combination of tumours to avoid misdiagnosis. We describe the finding of a rare collision tumour, mature cystic teratoma and ovarian fibroma complicated by torsion.