ENTEROGENOUS CYST OF THE ORBITAL APEX AND SUPERIOR ORBITAL FISSURE

Background: Enterogenous cysts of the central nervous system are rare congenital tumors with a single layer of mucin-secreting epithelial ce lls resembling gastrointestinal epithelium. The tumor is located most commonly at lower cervical and cervicothoracic spinal levels; only 22 intracranial cases have been reported. To the authors' knowledge, this entity has not been described in the orbit. Methods: A 23-year-old wo man with painful loss of vision and ophthalmoplegia in the left eye wa s treated with oral and intravenous corticosteroids for presumed orbit al inflammation. After a cystic lesion in the left orbital apex was de monstrated on computed tomographic scan and magnetic resonance imaging , various diagnoses, including optic nerve tumor, granulomatous inflam mation, lymphoma, vascular anomaly, and pseudotumor, were considered u ntil transcranial biopsy established the correct diagnosis. The tumor subsequently recurred twice. Results: More than 3 years after the last recurrence, the patient has no pain but has unilateral optic atrophy, significant visual field loss, limited motility, and an anesthetic co rnea in the left eye. Conclusion: The diagnosis of enterogenous cyst i s difficult without adequate biopsy because the radiologic and clinica l presentation of this rare tumor may be confused with other lesions. Previous attempts to explain intracranially placed enterogenous cysts offer no explanation for an orbital occurrence nor do they adequately describe a mechanism for an intracranial location in general. An embry ologically based explanation that takes into account the occurrence of this entity from the caudal to rostral extent of the neuraxis is desc ribed. This theory suggests that the orbit is the most rostral possibl e location for an enterogenous cyst.