*38 year-old woman with recurrent groin pain
What is the most likely diagnosis?
1. Malignant ovarian neoplasm
2. Ovarian dermoid cyst
3. Tuboovarian abscess
4. Endometrioma
Answer
Answer: Ovarian dermoid cyst
Case Discussion:
MR images demonstrate left ovarian mass containing fat and soft tissue. Left ovarian mass that contains: Fat (bright in T1 image and fat suppression in T1 fat sat and STIR images), soft tissue-dermoid plug (increased enhancement in T1+C fat sat images).
Ovarian dermoid cyst (also called mature cystic teratoma) is the most common ovarian neoplasm. It is slow-growing tumor. It contains elements from multiple germ cell layers. A dermoid plug (also known Rokitansky nodule) refers to a solid protuberance projecting from an ovarian cyst in the context of an ovarian dermoid cyst. Dermoid plug generally contains calcific, dental, adipose, hair and / or sebaceous components (1).
Ovarian dermoid cysts account for ~15% of all ovarian neoplasms. They are the most common ovarian neoplasm in patients younger than 20 years. They can be bilateral in 10-15% of cases (1-2).
Conventional radiograph can show calcific and tooth components in the pelvis. An ovarian dermoid is seen as a unilocular cystic adnexal mass with some mural components on ultrasound. CT images demonstrate fat areas with very low Hounsfield values, fat-fluid level, calcification, Rokitansky protuberance. Pelvic MRI shows the presence of fat. Fat suppression technique is used to differentiate between ovarian dermoid cyst and hemorrhagic cyst. Dermoid cyst contains fat and its signal will be suppressed in T1 fat sat and STIR images (2, 3).
References:
1. Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: tumor types and imaging characteristics. Radiographics. 21 (2): 475-90.
2. Fibus TF. Intraperitoneal rupture of a benign cystic ovarian teratoma: findings at CT and MR imaging. AJR Am J Roentgenol. 2000;174 (1): 261-2.
3. Patel MD, Feldstein VA, Lipson SD et-al. Cystic teratomas of the ovary: diagnostic value of sonography. AJR Am J Roentgenol. 1998;171 (4): 1061-5