Paleopathology of an ovarian teratoma: Description and diagnosis of an exotic abdominal bone and tooth mass in a historic Peruvian burial

• This case study describes a probable ovarian teratoma from Early Colonial Peru.
• The unusual abdominal abnormality consisted of 83 small, unclassifiable bones and 37 tooth-like elements.
• We consider issues in identification and recovery of these exceedingly rare neoplasms.

Neoplasms are among the most rarely described categories of skeletal abnormalities in paleopathology, and of these, bone- and tooth-forming ovarian teratomas may represent the most extraordinary and exotic. In this case study, we examine a bone and tooth mass found in an Early Colonial period burial from Eten, Peru. We document a complex array of 83 bony and 37 dental elements in the abdominal cavity of an adolescent female individual. The bones possess unclassifiable and non-functional morphologies, while the teeth tended to resemble incisors, canines, premolars, and molars but were more bulbous, smaller in size, and irregularly mineralized. We examine various differential diagnoses, including ectopic pregnancy, fetus in fetu or parasitic twin, lithopedia, and ovarian teratoma. We can confidently rule out the former three options, and the evidence is highly concordant with expectations of a mature ovarian teratoma. We also discuss a range of paleopathological and archaeological considerations for the identification, recovery, analysis, and prevalence of these distinctive neoplasms that are virtually unknown in the paleopathological literature.