Frontal Base Endodermal Cyst: A Case Report and Review of Literature

Background: Endodermal cyst (EC) is a rare congenital cyst of endodermal origin, but the pathogenesis of this entity remains uncertain. Supratentorial EC is particularly uncommon, but some cases have been reported. Here, we report a case of supratentorial EC that developed at the frontal base which indicates posttraumatic development rather than a congenital origin. Case Description: A 65-year-old man who had a history of orbital bone fracture without rhinorrhea sustained in a traffic accident presented with gradually enlarging frontal-base cystic lesions. Multiple cystic lesions were removed via left frontal craniotomy. The cysts showed no communication with the frontal sinus. Histological examination identified EC. Postoperative course was uneventful and no recurrences have been identified as of 2 years later. Conclusions: According to reported cases, unlike ECs in other intracranial locations, frontal base ECs tend to present at advanced ages. The present case also presented with EC enlargement at an advanced age and two lesions located at the bone hiatus in the frontal base that were presumably caused by trauma. It is possible that sinus communication was repaired as the bone fracture was remodeled, and the remnant sinus epithelial tissues developed into ECs over time. This situation makes it reasonable to presume a posttraumatic rather than a congenital origin. In conclusion, as for frontal base ECs, contrary to the traditional theory, the developmental mechanisms may not necessarily be congenital.