A ventral brainstem neurenteric cyst – A case report and review of the pre-brainstem location

Neurenteric cysts are uncommon, benign endoderm-derived lesions that result from aberrant embryologic development of the notochord. They are typically located in the intradural extramedullary spinal cord and rarely located intracranially. Contrary to spinal-located cysts, intracranial cysts are rarer in the pediatric population. Clinically, they may present with symptoms of mass effect, or they can be incidentally discovered. A 10-year-old healthy female child presented with recurrent headaches. The physical and neurological examination was unremarkable. Brain magnetic resonance imaging (MRI) showed a well-demarcated lesion anterior to the pontomedullary junction with striking T1 and T2/T2 fluid-attenuated inversion recovery high-signal intensity and a small rounded nodule within of low signal on T1, T2, and T2*. On initial conservative strategy with serial brain MRI, there was a progressive enlargement of the lesion with significant mass effect on the brainstem. The patient underwent a right retrosigmoid craniotomy, and the cyst wall was fenestrated and drained. Part of the cyst wall and the solid nodule were adherent to the brainstem and basilar artery and were not removed. The histologic findings were consistent with the diagnosis of a benign endodermal cyst. The postoperative period was uneventful. We report a successful surgical treatment of this rare congenital cyst located in the ventral brainstem. We present pre-and post-operative imaging findings, intraoperative microscopic images of the procedure, and a brief review of relevant clinical literature on the topic.