Subglottic Stenosis After Radioactive Iodine Treatment for Graves' Disease: A Case Report

Subglottic stenosis (SGS) is a narrowing of the airway below the glottis and may be congenital or acquired. While prolonged intubation is the most common cause of acquired SGS, other etiologies remain incompletely understood.

A 37-year-old woman presented with a four-year history of mild progressive stridor, dysphonia, and chronic cough. Her medical history was notable for Graves' disease, treated initially with long-term carbimazole followed by radioactive iodine (RAI). She had never been intubated and had no autoimmune or rheumatologic disease. Awake fiberoptic endoscopy raised suspicion of SGS, which was confirmed by preoperative magnetic resonance imaging.

Suspension microlaryngoscopy with biopsy and dilation revealed a Myer-Cotton grade II SGS with an irregular aspect and exposed cartilage. Histopathology demonstrated chronic inflammation, fibrosis, and reactive epithelial changes consistent with radiation-induced injury. After a second endoscopic dilation, only a minor anterior synechia remained, without evidence of recurrent stenosis.

This case report highlights a temporal association between RAI therapy and the subsequent development of SGS, supported by histopathological findings suggestive of radiation-induced tissue injury. In the absence of other established risk factors, RAI treatment may represent a rare but clinically relevant cause of acquired SGS, a complication not previously reported in the literature.