CONGENITAL ORBITAL CYSTS ASSOCIATED WITH THE COMMON SHEATH OF SUPERIOR RECTUS AND LEVATOR PALPEBRAE SUPERIORIS MUSCLES

Purpose: To review the clinical and operative features of a subgroup o f superior congenital orbital cysts that intimately are associated wit h the common sheath of the superior rectus and levator palpebrae super ioris muscles. Methods: Records from four eligible patients were revie wed retrospectively. Results: All four patients had ptosis or lid swel ling at initial presentation and were found at surgery to have large c ysts within the common tendon sheath of the superior rectus and levato r palpebrae superioris muscles. The lining of these cysts resembled th at of conjunctiva. There was no precedent conjunctival disease or surg ery. Conclusions: The authors propose that these cysts are congenital and arise as misdirected cleavage of mesoderm during formation of the superior fornix. As such, this type of cyst has not been described pre viously and may represent a third group of congenital orbital cysts di stinct from both conjunctival inclusion and dermoid cysts; Particular caution is required in their excision.