Malignant Transformation of a Brain Neurenteric Cyst: A Case Report.

BACKGROUND &

OBJECTIVE

Neurenteric cysts (NCs) are rare, benign congenital anomalies originating from the endoderm, and they rarely undergo malignant transformation. Only a small number of such cases have been reported in the literature.

CASE REPORT: A 55-year-old man presented with a one-month history of headache and diplopia. Magnetic resonance imaging (MRI) showed a 49 × 41 × 54 mm solid mass in the left frontal lobe, extending into the frontal, sphenoid, and ethmoid sinuses as well as the left orbit. The patient underwent craniotomy for tumor resection. Histopathology showed small remnants of a neurenteric cyst wall with squamous metaplasia and malignant transformation into squamous cell carcinoma (SCC). Immunohistochemistry revealed carcinoembryonic antigen (CEA) positivity in the cyst wall, focal epithelial membrane antigen (EMA) positivity in the tumor component, and diffuse nuclear expression of mutant p53 and Ki-67 in more than 80% of tumor cells.

CONCLUSION

We report a rare case of an intracranial NC that underwent malignant transformation into SCC. Intracranial SCC arising from an NC is uncommon. Moreover, unlike typical NCs, the lesion appeared as a solid mass without any visible cystic component on imaging, and cystic remnants were detected only microscopically. The absence of typical imaging features makes diagnosis challenging and highlights the importance of histopathologic examination for definitive diagnosis.