Cerebellopontine angle neurenteric cyst with focal malignant features.

Neurenteric cysts are uncommon cystic lesions lined by endodermal-derived epithelium, which are rarely found in the CNS, especially in the intracranial region. Although recurrences and disseminations of these cysts have been reported, only one case of intracranial malignant transformation has previously been described. Here we report a cerebellopontine angle neurenteric cyst in a 26-year-old woman. The cyst wall was lined by columnar epithelium with atypical nuclei and high MIB-1 index. In addition, stromal invasion was found in the subepithelial areas, which shows malignant features. Dissemination was speculated on MRI 6 months after total excision of the original cyst.