Extragonadal teratomas of the adult abdomen and pelvis: a pictorial review

Teratomas comprise a spectrum of tumours that have striking imaging appearances and are commonly considered when evaluating a mass in the female pelvis. A subgroup of these tumours located in an extragonadal abdominopelvic location, in contrast, are extremely rare and can affect both sexes. Extragonadal teratomas can occur at all ages, are particularly unusual in adults and can cause confusion in the differential diagnosis, especially in children. Familiarity with the imaging features of the spectrum of teratomas within the abdominal cavity is therefore of great importance, as radiological diagnosis can guide treatment, prevent delays in diagnosis and avoid sequelae. This article summarizes the radiological appearances of these rare extragonadal tumours in adults in relation to their pathology, malignant potential, location and behaviour. Although uncommon, teratomas should be considered in the differential diagnosis of extragonadal abdominal masses, particularly in young adults.Teratomas are neoplasms with tissue components resembling normal derivatives of the three germ layers. They comprise a spectrum of tumours with striking imaging appearances and are commonly considered when evaluating pelvic masses in females. Extragonadal abdominopelvic teratomas are, in contrast, very rare and are seen in both sexes. They represent only 1–5% of germ cell tumours (GCTs)¹ and therefore may not be readily considered by clinicians. Their radiological appearances are, however, characteristic, and familiarity with these features will lead to more accurate radiological diagnoses that not only guide treatment but also prevent avoidable complications from diagnostic delay.Teratomas can present at any age. They contain tissue elements foreign to the organ or anatomic site of origin.² Arising from totipotent germ cells, they contain derivatives of one to all three germ cell layers (the ectoderm, endoderm and mesoderm)^2–4 and occur most frequently in the ovary or testis. Gonadal teratomas are well described; however, the extragonadal variants are under-represented in the literature. These encompass mature cystic teratomas (MCTs), which are most frequently tridermal lineage, and epidermoid cysts, which are frequently classified pathologically as monodermal teratomas (MTs) (