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Reproductive/Endocrine Imaging

E2602. Ovarian Mature Cystic Teratoma (Dermoid): Review of Ultrasound Features

Lim K. Pennsylvania Hospital, Philadelphia, PA

Address correspondence to K. Lim (khengll@yahoo.com)

Background Information: Mature cystic teratomas (MCTs) and serous cystadenomas are the two most common ovarian neoplasms encountered in clinical practice. Majority of ovarian masses encountered in clinical practice is benign. Approximately 15–25% of ovarian neoplasms are MCTs, also known as dermoids. Ultrasound (US) is often the first imaging test in the diagnosis of an ovarian mass across all ages. In the United States, there is a propensity for follow-up MRI and CT when an ovarian mass is encountered by US. US has multiple desirable attributes, which include wide availability, relatively quick procedure, no peripheral IV catheter placement for iodinated or gadolinium contrast injection, lack of ionizing radiation, and relatively low cost. The purpose of this exhibit is to review the sonographic features of MCTs with correlation to CT and MRI, as well as correlation to the various components of the three germ layers found in ovarian MCTs.

Educational Goals/Teaching Points: The goal of this exhibit is to improve the diagnostic accuracy of radiologists and physicians in the interpretation of pelvic ultrasound. We will discuss the imaging features that help differentiate immature ovarian teratomas and malignant degeneration of MCTs from benign MCTs. We will also discuss complications of ovarian MCTs, such as torsion and rupture, as well as pitfalls in sonographic diagnosis, such as acute hemorrhage in ovarian cyst or endometrioma, pedunculated lipoleiomyoma, and perforated appendicitis with appendicolith.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: Sonographic features of ovarian MCTs include homogenously hyperechoic mass, hyperechoic interface causing acoustic shadowing, echogenic dermoid plug with shadowing, internal echogenic reticulations, fat-fluid level, and rarely, echogenic spheres within the mass. We will present case examples ranging from malignant degeneration of MCTs to squamous cell carcinoma and some teaching points. For example, avoid cursory transabdominal examination of the uterus and ovaries as ovarian MCT may not be best visualized on transvaginal ultrasound. Case illustration of this is presented. If a mass is palpable on physical examination but initial ultrasound scan appears normal, further scan should be performed attentively. An ultrasound case of MCT resemblance to bowel and pelvic fat is presented. Diagnosis of MCTs should include a cine clip to demonstrate the full extent of the ovarian MCTs and to avoid pitfalls.

Conclusion: Knowing that the pretest probability of ovarian masses encountered in clinical practice favors benignity, along with optimizing scanning technique, in most cases, US can be used as the sole imaging modality in diagnosing ovarian MCTs. CT and MRI are helpful for problem solving if US features of ovarian MCTs are equivocal.