<b>Introduction:</b> Recurrent thyroglossal duct cyst after surgery is not a rare condition and first-line treatment has not been established yet.<br/><br/> <b>Aim:</b> Evaluation of outcomes and complications of OK-432 treatment in patients with recurrent thyroglossal duct cyst after surgery. <br/><br/> <b>Material and methods:</b> This study is designed as a case series with planned data collection at Tohoku Medical and Pharmaceutical University and Fukase Clinic. Five patients with recurrent thyroglossal duct cyst after surgery received this therapy between January 2014 and February 2020 on an outpatient basis, without hospitalization. OK-432 solution was injected into the lesion using an 18- or 27-gauge needle, depending on the location and size of the lesion, as well as on possible complications.<br/> <br/> <b>Results:</b> Lesions showed marked reduction or total shrinkage in all patients, with no local scarring or deformity at the injection site. Side effects manifested as local pain at the site of injection and fever (37.5-38.5°C) observed in three patients, but the symptoms resolved within a few days.<br/> <br/> <b>Conclusions:</b> Since OK-432 therapy is simple, easy, safe and effective, it can be used as an alternative to surgery in the treatment of recurrent thyroglossal duct cyst after surgery.
Keywords: OK-432; recurrent thyroglossal duct cyst; surgery.