ARRS 2022 Abstracts

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E1214. Benign Fat Behaving Badly: A Review of Ovarian Teratomas and Their Complications
Authors
  1. Joshua Parker; ProMedica; University of Toledo
  2. Sarah Abdulhamid; ProMedica; University of Toledo
  3. Michael Walsh; ProMedica; University of Toledo
Background
Ovarian teratomas are the most common type of germ cell tumor and account for 50% of pediatric ovarian tumors and 20% of adult ovarian tumors. Mature ovarian teratomas are composed of well-differentiated tissues of two or three germ cell layers (ectoderm, mesoderm, and endoderm). Similarly, immature teratomas also contain tissues from two or three germ cell layers but may include poorly differentiated elements. Because of the many possible combinations of tissue types, teratomas have a wide variety of imaging features. Fortunately, the presence of intratumoral fat is diagnostic. Teratomas of any kind also have the potential for various complications, including torsion, rupture, malignant transformation, pseudomyxoma peritonei, infection, autoimmune hemolytic anemia, and encephalitis. We will discuss different imaging features and complications to promote accurate recognition and diagnosis of these entities.

Educational Goals / Teaching Points
Teratomas are the most common type of germ cell tumor. They have a variable appearance and the potential for multiple complications. Uncomplicated teratomas are readily identified on modern imaging due to the presence of intratumoral fat. Rupture is diagnosed when there is discontinuity of the tumor wall. Unexplained distortion should also raise concern for rupture. Secondary complications of rupture include ascites, peritonitis, and tumor deposits throughout the abdominopelvic cavity.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Classic ovarian teratomas are cystic masses with intratumoral fat. The most common ultrasound manifestations are a dermoid plug, the "tip of iceberg" sign, and the "dermoid mesh" sign. Other findings include calcified teeth/bone, fluid-fluid levels, and mobile nodules of varying echogenicity. Diagnosis with cross-sectional imaging is more straightforward as the presence of intratumoral fat, which is present in more than 90% of cases, is diagnostic of an ovarian teratoma. Teratomas may demonstrate post-contrast enhancement, but this is not always reflective of malignancy. Rupture occurs in up to 4% of ovarian teratomas. Discontinuity of the wall is the most obvious imaging finding on ultrasound, CT, or MRI; however, unexplained distortion or flattening should also raise suspicion for rupture. Ascites is an additional, but nonspecific, finding. Pseudomyxoma peritonei is a possible complication if the teratoma contains mucinous elements. Seeding of the peritoneal cavity results in mucinous ascites and characteristic scalloping of the surface of the liver. There is relative sparing of the small bowel and mesentery.

Conclusion
Ovarian teratomas are the most common type of germ cell tumors, but the clinical manifestations and imaging findings are highly variable. Additionally, teratomas have a wide variety of complications, each of which requires specific management. With familiarization of these complications and findings, accurate diagnosis by imaging will lead to proper treatment and improved outcomes.