A 24-year-old woman with a history of congenital endotropia and medial rectus surgery at the age of 3 years. On examination she had residual endotropia and DVD. Surgery was performed according to the technique of lateral rectus resection and retoinsertion of both superior rectus loops. Four months after surgery, she presented a cystic conjunctival lesion with signs of inflammation in the upper nasal sector of her left eye. Drainage was performed and a mucopurulent liquid was obtained, which led to a diagnosis of subconjunctival abscess. Treatment was started with topical ciprofloxacin and dexamethasone and systemic ciprofloxacin. After one month the lesion recurred without inflammatory signs and progressive growth was observed. Complete surgical excision of the lesion, which is adjacent to the primitive insertion of the upper rectum, was performed. The histopathological diagnosis was a benign cystic lesion. The study revealed the existence of a cystic formation with a fibrous wall including vessels and some lymphoid aggregates, partially lined on the inner surface by a flat stratified epithelium, with no significant atypia or mitoses. After surgery the lesion did not recur.