Neurenteric cysts are "rare benign mass forming developmental abnormalities" that usually affect young adults.
Neurenteric cysts are thought to be derived from primitive endoderm, and form as a result of faulty endodermal-notochordal separation at 3 weeks of embryogenesis.
Neurenteric cysts are lined by simple-to-pseudostratified respiratory/gastrointestinal-like epithelium; as such, these lesions closely resemble
colloid and
Rathke's cleft cysts. Anatomically,
neurenteric cysts most frequently arise in an intradural-extraaxial location anterior to the cervical-thoracic spinal cord. Intracranial
neurenteric cysts are uncommon but have a tendency to reside in the infratentorial compartment. Malignant transformation of the epithelial component of
neurenteric cysts is decidedly rare. Of the 3 reported cases of
neurenteric cysts with malignant transformation, all were intracranial (2 infratentorial and 1 supratentorial) and extraaxial. We describe a 58-year-old female with a supratentorial-intraaxial lesion that is consistent with a
neurenteric cyst exhibiting malignant transformation into an invasive mucinous
papillary cystadenocarcinoma. Areas of direct transition between typical benign
neurenteric cyst epithelia and malignant epithelia (i.e.,
carcinoma in situ), highlighted by an abrupt change in the Ki-67 proliferative index, were identified, and supported the primary nature of this
brain neoplasm. Metastatic workup at the time of presentation was unremarkable, and immediately up until being lost to follow-up 38 months after gross total resection, routine follow-up MR imaging had not detected a recurrence. To our knowledge, this would be the first reported case of malignant transformation within a supratentorial-intraaxial
neurenteric cyst.