OVARIAN DERMOID

Parasagittal T1, T2 and STIR images:
Well defined round thin walled cystic lesion in ovary. The cyst is hyperintense on T1 and T2 wt images which is suppressed on STIR images- suggestive of lipid material. An irregular T1 isointense and T2 hyperintense solid component within the cyst which is hyperintense on STIR images.



·        Mature cystic teratoma(dermoid) is the most common germ cell neoplasm.

·        They affect a younger age group (mean patient age, 30 years) than epithelial neoplasms.

·        Most mature cystic teratomas are asymptomatic.

·        Grow slowly at an average rate of 1.8 mm each year, prompting some investigators to advocate nonsurgical management of smaller (<6-cm) tumors.

·        The tumors are bilateral in about 10% of cases.

·        Three patterns on ultrasound

1.     Cystic lesion with a densely echogenic tubercle (Rokitansky nodule) projecting into the cyst lumen

2.     Diffusely or partially echogenic mass with the echogenic area usually demonstrating sound attenuation owing to sebaceous material and hair within the cyst cavity

3.     Multiple thin, echogenic bands caused by hair in the cyst cavity

·        At CT, fat attenuation within a cyst, with or without calcification in the wall, is diagnostic for mature cystic teratoma.

·        At MR imaging, the sebaceous component is hyperintense on T1 and variable on T2. The imaging appearance on T1- and T2-weighted images is therefore mimicked by some hemorrhagic lesions, most prominently endometriomas.

·        Sequences with frequency-selective fat saturation or Gradient-echo imaging with an echo time in which fat and water are in opposite phase can be used to distinguish fat from blood products.

·        Complications

1.     Rupture

2.     Malignant degeneration

3.     Torsion

Reference :    Ovarian Teratomas: Tumor Types and Imaging Characteristics, March 2001 RadioGraphics, 21, 475-490.