Supratentorial neurenteric cyst with spontaneous repetitive intracystic hemorrhage mimicking brain abscess: a case report.

Neurenteric cyst (NC) is a benign epithelial cyst (BEC) of endodermal origin that mostly occurs in the spinal subdural space or posterior cranial fossa. A 28-year-old male presented with a left frontal lobe NC associated with spontaneous repetitive intracystic hemorrhage, which was initially diagnosed and treated as a brain abscess. He presented with headache and disorientation, without underlying diseases. A cystic tumor was suspected because of a hypointense signal on diffusion-weighted magnetic resonance imaging (MRI). One day after admission, his condition deteriorated rapidly and emergency cyst aspiration was performed. A brown viscous liquid like bloody pus comprising many neutrophils and macrophages was obtained. Although culture was negative, we initially started antibiotic treatment because of cyst content characteristics and rapid clinical course compatible with brain abscess. He was discharged without neurological deficits, but occasionally complained of intense headache. Computed tomography/MRI showed repetitive intracystic hemorrhage and gradual re-enlargement of the lesion. He underwent radical cyst excision by frontal craniotomy 34 months after aspiration. The pathological diagnosis was NC. We believe this is the first report of a supratentorial NC with spontaneous repetitive intracystic hemorrhage. BECs, especially with intracystic hemorrhage, are difficult to be distinguished from brain abscesses. In cases of cystic lesions or presumed brain abscesses refractory to treatment with aspiration and/or antibiotics, BECs should be considered, and radical cyst wall removal should be considered a treatment option.