factoid: Ovarian Teratoma
-derivative of 3 germ cell layers
-typically occurs in childhood or adolescence (most common ovarian mass in children)
-up to 16% chance of torsion especially if >11cm
-most are mature (benign)
-<2% are immature
US: Many presentations:
1. Cystic lesion with echogenic tubercle (Rokitansky nodule) projecting into the cyst
2. Diffusely or partially echogenic mass with the echogenic area usually demonstrating sound attenuation owing to sebaceous material and hair within the cyst.
3. Multiple thin, echogenic bands caused by hair in the cyst cavity.
4. Pure sebum within the cyst may be hypoechoic or anechoic.
5. Fluid-fluid levels result from sebum floating above aqueous fluid, which appears more echogenic than the sebum layer.
6. Diffuse echogenicity in these tumors is caused by hair mixed with the cyst fluid.
CT: fat attenuation within a cyst, with or without calcification in the wall, is diagnostic. A floating mass of hair can sometimes be identified at the fat–aqueous fluid interface. Fat is reported in 93% of cases and teeth or other calcifications in 56%.
reference: Radiology Review Manual, Wolfgang Dahnert
Core Curriculum: Ultrasound, William Brant
Ovarian Teratomas: Tumor Types and Imaging Characteristics, Outwater, Erik, et al., Radiographics. 2001;21:475-490.
imageCaption: There is a large pelvic mass extending up into the abdomen. Largest transverse dimension is19 cm. It is predominantly fluid in density with scattered areas of soft tissue, fat and calcium throughout.