RESUMEN
BACKGROUND: Teratomas of the greater omentum are rare. In most cases, they are composed of mature tissue elements and behave clinically in a benign fashion. CASE: A 62-year-old woman with a history of bilateral salpingo-oophorectomy due to ectopic pregnancy was found to have multiple cystic teratomas of the omentum. There was a histologic evidence of a sequential transition from benign through borderline to obviously invasive adenocarcinoma within the lining of the cysts as well as peritoneal dissemination. CONCLUSION: We defined the present case as malignant transformation of a mature teratoma, but have no evidence whatsoever for the origin of multiple mature teratomas. Further detailed analyses with more elaborated procedures on many relevant reports would be required to establish the origin and biologic behavior of teratomas of the omentum.