Radiation-induced lung injury due to extra thoracic irradiation

Background: To describe three cases of radiation-induced lung injury (RILI) occurring outside the radiation field and to review clinical, radiologic, and histologic aspects of RILI outside the radiation field. Methods: We present case reports of three men with a mean age of 57.6 years, who had received radiation therapy and concomitant chemotherapy for supraglottic and laryngeal carcinoma. A detailed clinical, radiological, and laboratory evaluation was carried out to confirm the diagnosis. Results: All our three patients developed radiation pneumonitis about 4 to 8 weeks after the completion of radiotherapy. All the three patients received radiation in the neck region. The lung infiltrates had developed outside the radiation field. Computed tomography of the chest showed ground glass opacity in the lower lung zones. One patient had grade 2 radiation pneumonitis, while the other two had grade 1. Two patients had grade 1 radiation pneumonitis spontaneously resolved, while one patient was advised inhaled steroids, though he was lost to follow-up. Conclusions: RILI may occur away from the site of irradiation due to immunological and non-dosimetric factors. It is important to diagnose RILI at the earliest as management would vary with the grade of RILI. Grade 1 RILI may resolve spontaneously.