Orbital lymphatic malformations are rare congenital choristomas associated with pain, proptosis, exposure keratopathy, and vision loss. Current treatments of surgery, drainage, and sclerotherapy may have adverse effects including risk of damage to surrounding structures, swelling, and malformation persistence or recrudescence. Sirolimus, which inhibits mammalian target of rapamycin, a regulator of cell growth and vascular endothelial growth factor expression, has successfully treated systemic vascular malformations. However, its efficacy and safety have not yet been well established for orbital lymphatic malformations.
Systematic review and analysis of relevant published literature were performed. PubMed, Embase, and World of Science searches were conducted for studies involving sirolimus treatment of orbital lymphatic malformations through July 2019.
Nine case series and reports with 10 total patients who received sirolimus for treatment of orbital lymphatic malformations were included. The age at sirolimus initiation ranged from 1 week to 23 years. The malformation was lymphatic in 6 patients, lymphaticovenous in 3 patients, and lymphatic-arteriovenous in 1 patient. Six patients underwent ineffective prior therapy including sclerotherapy, surgery, or medical therapy. Initial sirolimus dosage ranged from 0.05 mg/kg twice a day to 1 mg twice a day, and duration ranged from 6 months to 53 months. Seven patients had partial response, and 3 patients, all of whom had a microcystic malformation component, experienced complete response. Adverse effects included mild reversible leukopenia, hypertriglyceridemia, hypercholesterolemia, and transaminitis with adverse effects denied or not specified for 6 patients.
Sirolimus may be a safe and effective treatment for orbital lymphatic malformations, especially microcystic malformations.