Congenital naso-orbital meningocele in a lamb: a case report

The subject of this report is a rare case of naso-orbital meningocele concurrent with right cerebral hemisphere hydranencephaly and agenesis of corpus callosum in a newborn lamb. Our necropsy findings revealed that the bulging sac containing CSF extends into the skull bony and dural defects, through which the cyst protrudes into the orbital and nasal cavities. Also, histological and immunohistochemical demonstrations of the cyst wall showed that the inner layer is composed of meningeal components. These findings support the diagnosis of a naso-orbital meningocele. This case is an unusual presentation of a rare congenital skull defect and associated anomalies in veterinary literature.