Presentation
The patient presented with epigastric pain, nausea, and vomiting. She also reported chronic left hip pain.
Patient Data
AP radiograph of the pelvis shows two tooth-like calcifications in the right pelvis.
No acute fracture or dislocation is seen. A small ossific fragment along the left lesser trochanter appears chronic. The hip joint spaces are maintained.
CT of the abdomen and pelvis with IV contrast shows a heterogeneous right adnexal mass, containing fat, layering sebaceous fluid, and peripheral bone/tooth density. There is a fat-containing nodule protruding at the fat-fluid interface of the cystic mass; this has been previously described as the floating ball sign or Poké Ball sign (pareidolia). The peripheral tooth density may be within a mural nodule which is consistent with a Rokitansky nodule / dermoid plug. The findings are compatible with a mature cystic ovarian teratoma.
There is no free fluid.
An IVC filter is present.
Case Discussion
Ovarian teratomas include monodermal teratomas, immature teratomas, and, in the case presented, mature cystic teratomas. These are often discovered incidentally during imaging conducted for other medical reasons 1.
Most mature cystic teratomas, which are often characterized by sebaceous material and calcification, can be diagnosed using ultrasonography, but their diagnosis via this modality can be complicated due to the tumor's variety of appearances. As a result, the use of CT and MR imaging can prompt a more straightforward diagnosis due to these modalities being more sensitive for fat 3. On CT and MR imaging, mature cystic teratomas may manifest as a cystic lesion with a floating ball at the fat-fluid interface, often likened to a "Poke Ball" 2,3. In this case, a floating ball is observed in the lesion as well as two tooth-like calcifications.
Patients may be asymptomatic or exhibit chronic pelvic pain. However, acute pain may indicate potential complications, such as torsion or rupture 1. In this case, the cause of the patient's abdominal pain was presumed to be gastritis. The ovarian teratoma was likely asymptomatic, and therefore, no intervention was performed.
Case co-author: Roger Grayson Axtell (Midwestern University)
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