An Imaging Mimicry: A Case Report of Mature Cystic Teratoma or Fat-Containing Lesion: Cystic Teratoma or Lipomatous Lesion

Abstract

A 52-year-old female patient with a history of autoimmune thyroiditis was diagnosed with a pelvic mass that was initially thought to be an ovarian dermoid cyst, also known as a mature cystic teratoma, on abdominal/pelvic CT imaging in 2017. Later, from 2019 to 2023, various imaging modalities such as CT and MRI revealed that the growing mass developed a cystic component that became encapsulated. Thus, we conclude this mass was likely a lipomatous lesion that underwent fat necrosis due to local inflammation rather than a dermoid cyst. The emergence of a mixed solid and cystic mass with features suggestive of a lipomatous lesion following the disappearance of a left ovarian cyst presented diagnostic challenges. This case emphasizes the pathophysiological aspects of fat necrosis and dermoid cysts, the complexity of discerning between the two on imaging, and the need for a comprehensive, collaborative diagnostic approach between radiologists and other clinicians.