What is the time of occurrence for Radiation pneumonitis?
Nonspecific symptoms begin 1 to 6 months after radiation therapy has been completed and include fever, weight loss, dry cough, and dyspnea. Physical examination of the chest usually shows only skin changes from radiation exposure and the occasional presence of a pleural rub. The disease can be severe, with progression over days to weeks leading to acute respiratory failure. The clinical and radiographic worsening over days to weeks is a helpful clue to distinguish radiation pneumonitis from recurrent local or metastatic cancer. The radiographic features typically consist of alveolar opacification of the irradiated portion of the lung with occasional air bronchograms. As confluence progresses, a nonanatomic “edge” may be seen on the chest radiograph, which reflects the border of the radiation port. Radiation pneumonitis can occur even outside the radiation field and rarely affects the contralateral lung.