Ovarian mature cystic teratoma - dermoid cyst
A 55 year old lady presented with severe onset right flank pain. Urinalysis showed haematuria. A CT KUB was performed to investigate for renal tract calculi.
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CT KUB showed no renal or ureteric calculi but there is a 12.5cm x 10cm right pelvic mass in the right adnexa. It contains fat and dentiform calcification in keeping with an ovarian dermoid cyst.
A CT KUB is a common investigation requested by the emergency department for possible renal tract calculi as a cause of flank pain. Often other pathology can be identified on these CT scans which may be accounting for the patient's symptoms in the absence of calculi, such as a dermoid cyst. On CT fat attenuation in a cyst, with or without calcification of the cyst wall is considered diagnostic of a dermoid (1,5).
Many dermoids (often referred to as mature cystic teratomas) are usually asymptomatic. However complications such as torsion, malignant degenertaion or rupture can occur. Usually when a dermoid is complicated by torsion they are typically large, (mean diameter 11cm, versus 6cm). The size of the dermoid may be soley due to the dermoid or it may be that the torsion itself causing engorgement may account for some of this size. Findings such as vessel engorgement or deviation of the uterus to the side of the torsion, a mass with a high T1 signal-intensity rim on MRI or a low signal-intensity torsion with no enhancement due to blood vessels draping around the mass (1,2,3,4), may indicate torsion.
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