Radiology Resident Case of the Week

Cystic Teratoma

October 13, 1995

Etiology/Pathophysiology:
Teratomas are also called dermoid cysts. dermoids are composed of mature epithelial tissues, a combination of skin , hair, desquamated epithelium, and teeth. These masses also contain pure sebum which provides a fluid of lipid density on radiographs.

Pathology:
Dermoids are present at birth and are usually detected in young women during there second or third decade of life due to there slow growing potential. They account for 10%-15% of all ovarian neoplasms. They are benign ovarian tumors and bilateral in 10% of cases. 1% undergo malignant transformation to any of the component elements. Most commonly squamous cell carcinoma. Thyroid caricinoma and melanoma have also been noted. The karyotype of all benign ovarian teratomas are 46xx. Malignant lesions are commonly noted in prepubertal adolescents and young women with a mean age of 18years.

Miscellaneous:
Surgical removal usualy provides cure. However removal should be delayed 1 or 2 months if a hemorrhagic cyst is a consideration.

Imaging:
Ultrasound: complex mass with echogenic component, 60% have an echogenic focus with acoustic shadowing. Shadowing is due to calcification, mixed sebum and hair. Usually a predominately cystic mass ( 25-44%), solid( 10-31%), purely cystic ( 9-15%).

CT: Round mass of fat density floating in an interface between two water density components (93%). Globular calcification or rim of calcification have been noted 56% of the time. A ÒbullÕs eyeÓ sign is also described, consisting of a low density center and a high density rim of calcification.

DDx: