Correct answer is: Dermoid cyst

Dermoid cysts account for 15% of all ovarian neoplasms and predominate in young women, being the most common ovarian neoplasm in patients younger than 20 years. Ultrasound is the preferred imaging modality. Typically, an ovarian dermoid is seen as a unilocular cystic adnexal mass with some mural components. The spectrum of sonographic features includes: a diffusely or partially echogenic mass with posterior sound attenuation owing to sebaceous material and hair within the cyst cavity; an echogenic interface at the edge of the mass that obscures deep structures (the tip of the iceberg sign); mural hyperechoic or Rokitansky nodule (dermoid plug); echogenic shadowing calcific or dental (tooth) components; fluid-fluid levels; multiple thin echogenic bands caused by the hair in the cyst cavity; the dot-dash pattern (dermoid mesh); no internal vascularity on color Doppler; intracystic floating balls sign (uncommon, but characteristic).

Discussion

Among the alternatives, the diagnosis of dermoid cyst should be considered because ovarian serous or mucinous cystadenoma/cystadenocarcinoma is usually only a serious consideration if the typical features of dermoid cyst are absent. Carcinoma also tends to occur in an older age group than dermoid cysts. Ovarian dysgerminomas are rare ovarian tumors that occur predominantly in young women in the 2nd to 3rd decades. Approximately 10-20% of cases occur in pregnancy. On ultrasound, they may be seen as a septated ovarian mass with varying echotexture. Color Doppler ultrasound may show prominent flow signal within the fibrovascular septa. Fibromas occur at all ages but are most frequently seen in middle-aged women, and on ultrasound manifest as solid, hypoechoic masses with ultrasound beam attenuation. As such, they may appear similar to a pedunculated subserosal uterine fibroid. However, the sonographic appearance can be variable, and some tumors can have cystic components, although rarely.

Take home message

Knowing the ultrasound aspects of dermoid cysts is important because they are benign lesions that grow slowly (1-2 mm per year) and, therefore may not need surgery. The most common complication is ovarian torsion, which occurs in 3-16% of dermoid cysts. Many recommend annual follow-up for lesions <7 cm to monitor growth. Tumors larger than 7 cm should be resected.

References

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