Endodermal cyst: rare intraaxial brainstem location. Illustrative cases

BACKGROUND: This report detailed an extremely rare location of an endodermal cyst. Such location of the tumor can pose radiological confusion and a therapeutic dilemma. However, when identified, it can be a pleasant surprise for the surgeon and provide the possibility of a symptom-free long life for the patient. OBSERVATIONS: This report discussed two young patients who presented with relatively short-duration reports of ataxia and diplopia. Investigations revealed intraaxial brainstem lesion. During surgery, thick, pus-like fluid was evacuated and part of a wall was resected. Histology revealed that the lesion was an endodermal cyst. Both patients are well and are lesion- and symptom-free for 24 and 72 months. LESSONS: Endodermal cysts are some of the few long-standing and benign intraaxial brainstem lesions.