[Supratentorial endodermal cyst. Case report]

Endodermal cysts (EC) of the central nervous system are very uncommon lesions predominantly located in the spinal canal. Although rare, intracranial EC have been mainly described in the posterior fossa, with the supratentorial location considered exceptional. Apart from the low frequency of these lesions, their pathoembriology still remais unknown. We report a patient with a huge frontal EC and review the literature. A 62-year-old man presented with abnormal behaviour, disorientation and decreased level of consciousness after moderate head injury. Initial cranial CT scan revealed a large cyst in the left frontal region with marked midline shift. Emergency puncture and decompression of the cyst demonstrated a milky fluid with high protein levels. Cranial MRI after patient improvement confirmed the existence of the cystic lesion with less mass effect. Delayed surgery was performed with craniotomy and total removal of the cyst. Pathological examination confirmed the presence of a typical EC. Patient made a complete recovery on follow-up with no recurrence on postoperative MRIs. Differential diagnosis of EC based on radiological data is quite difficult. As aggresive behaviour of this condition has been described following incomplete resections, the treatment of choice is a radical removal of the cyst in one or two stages depending on patient clinical condition.