Central nervous system mature teratoma producing carbohydrate antigen 19-9: illustrative case

BACKGROUND: Central nervous system (CNS) mature teratoma is a rare disease with symptoms that can vary according to tumor location. Most lesions are benign; rarely, malignancy can develop in any of the somatic components. Elevated levels of tumor markers such as α-fetoprotein and β-human chorionic gonadotropin are not usually found in patients with CNS mature teratoma, and no reports have described an association with carbohydrate antigen 19-9 (CA19-9). OBSERVATIONS: A 64-year-old woman with headache was found to have a mass lesion in the anterior cranial fossa. Magnetic resonance imaging of the brain suggested a mature teratoma. Serum and cerebrospinal fluid (CSF) tests showed significant CA19-9 elevations (2,770 U/mL and 4,387 U/mL, respectively). Other examinations, including whole-body (18)F-fluorodeoxyglucose positron emission tomography, did not detect the origin of elevated CA19-9, suggesting that the high CA19-9 levels were caused by intracranial tumor. The patient underwent tumor removal. The histopathological diagnosis was mature teratoma with positive CA19-9 staining. CA19-9 levels in serum and CSF decreased significantly after tumor removal. LESSONS: The histopathological findings and postoperative decreased CA19-9 levels established the diagnosis of CA19-9–producing CNS mature teratoma. CNS mature teratoma can cause elevations in CA19-9 in cases with absence of neoplasms in the trunk.