Purpose: To report the nature of the contents of a cyst associated with microphthalmia and optic nerve coloboma in a male infant.
Design: Clinicopathologic report.
Case report: A male infant in good general health presented with a massively swollen, protruded left lower eyelid since birth. The globe was not identifiable. MRI disclosed a microphthalmic globe in the upper nasal orbit and an orbital cystic mass consisting of various compartments. Examination of the fellow eye showed a large optic nerve coloboma. As the protrusion of the left lower eyelid was progressive, aspiration of the cyst was performed twice. Finally, the cyst was removed surgically due to repeated filling.
Results: Examination of the aspirated fluid showed resemblance to cerebrospinal fluid (CSF). During surgery, the cyst was not found to communicate with the cerebrospinal fluid system. However, tissue resembling choroidal plexus lined the wall of the cyst that was adherent to the optic nerve. Histological evaluation of the tissue revealed ependymal cells.
Discussion: The presence of CSF in microphthalmic cysts does not necessarily imply a connection to the CNS, but may be due to local CSF production by ectopic ependymal cells.