S5452 Mature Cystic Perihepatic Teratoma Arising From the Lesser Omentum in an Adult Woman: A Rare Extragonadal Presentation

Introduction: Teratomas are rare germ cell tumors typically found in the gonads but can occasionally occur in extragonadal sites due to aberrant germ cell migration. Hepatic teratomas are extremely rare, accounting for only about 1% of such cases. This report presents a mature cystic teratoma of the liver in an adult woman. Case Description/Methods: A 38-year-old woman came in with several months of intermittent abdominal bloating and early satiety, which tended to get worse after meals. She felt otherwise well and had no weight loss, jaundice, bleeding, or other concerning symptoms. She had mild tenderness in the epigastric and right upper quadrant areas on the exam. Laboratory work, including liver function tests and tumor markers such as CEA and AFP, was normal. Tests for infections, including Echinococcus, tuberculosis, and stool parasites, were all negative. Imaging with magnetic resonance imaging and magnetic resonance cholangiopancreatography revealed a large, complex cystic mass, nearly 20 cm in size, sitting near the left lobe of the liver. It contained internal nodules and material that looked like blood, protein, and fat. Based on these findings, the initial differential included a hemorrhagic hepatic cyst, hydatid disease, or biliary cystadenoma. She underwent an exploratory laparotomy, which revealed the mass was arising from the lesser omentum, not the liver itself, but closely abutting it. It was removed intact. Pathology showed a mature cystic teratoma with components from all 3 germ layers, including skin with sebaceous glands, mucinous epithelium, and nerve tissue. She recovered well and was discharged without complications. Discussion: Teratomas are rare tumors that can contain a mixture of tissues, such as skin, hair, or glands. They usually develop in the ovaries or testes, but in rare cases, they can grow in unusual places if early germ cells settle outside their standard developmental path. A teratoma forming near the liver—known as a perihepatic teratoma—is highly uncommon and accounts for less than 1% of all cases. These tumors are often discovered incidentally or when they grow large enough to cause pressure symptoms, such as bloating or early fullness after eating, which was the case with our patient. Fortunately, perihepatic teratomas are typically well-encapsulated and can be removed entirely through surgery. While most are benign, there is a small risk, around 2 to 3%, of malignant transformation, most often into squamous cell carcinoma.