Introduction Rosai–Dorfman–Destombes disease (RDD) is a rare non-Langerhans histiocytic disorder with occasional extranodal involvement. Orbital disease can mimic neoplastic or inflammatory conditions, leading to diagnostic and therapeutic challenges. Standardized management strategies remain undefined. Aim To describe the diagnostic complexity and therapeutic role of radiation therapy, including re-irradiation, in orbital RDD. Case presentation A 58-year-old male presented with nasal obstructio