This is a typical small ovarian dermoid cyst as seen on transvaginal sonography using a high-end ultrasound machine.
Dermoid cysts, also known as dermoids and often referred to as mature cystic teratomas, are the most common germ cell tumors of the ovary in women of reproductive age. These lesions are usually asymptomatic until they reach considerable size. Frequently, ultrasonography is diagnostic. Hyperechoic areas are a highly ­predictive feature of ovarian dermoids, particularly when they are associated with distal acoustic shadowing. Such hyperechoic areas are not usually as intensely echogenic as calcification, but they are hyperechoic relative to adjacent soft tissues. Hyperechoic lines and dots, often known as the dermoid mesh, are also very predictive. Less common but also characteristic are a fluid-fluid level and floating globules. Discovering any two or more of the above features in a mass is particularly predictive of a dermoid. Calcification, often due to bone or a tooth, occurs in some dermoids, but cannot be used alone as definitive evidence of a dermoid since other neoplasms can also calcify.
The value of transvaginal ultrasound in evaluating dermoid cysts is well documented. Because of the improved resolution of transvaginal ultrasound, it should be used whenever possible. When an adnexal mass is large or beyond the field of view of the transvaginal probe, transabdominal scanning is recommended. Transabdominal scanning will often provide an overview of the relationship of the mass to the rest of the pelvic structures.
Color or power Doppler ultrasound is also needed to ensure that no blood flow exists in the solid elements of the mass. Color or power Doppler ultrasound requires proper technique to prevent erroneous interpretation. Multiple parameters, including gain and pulse repetition frequency, need to be optimized to detect slow flow.
Adnexal masses with features classic for an ovarian dermoid cyst do not usually need other imaging modalities to establish the diagnosis but should be followed with ultrasound at an initial interval of between 6 months and 1 year, regardless of age, if they are not removed. The purpose of follow-up is to ensure that the lesion is not changing in size or internal architecture.
Stavros Mousourakis (Mussurakis), MD, FRCR
Clinical Radiologist
Ultrasound, Fetal & Women's Imaging Specialist
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