IS Case 585: Radiation pneumonitis
Imaging Sciences URMC 2010
Publication Date: 2011-11-17
Patient is a 67-year-old male with rectal adenocarcinoma and a metastatic left upper lobe (LUL) lung mass status post video-assisted thoracoscopic surgery (VATS) resection and postoperative radiation therapy for follow-up.
This patient with known rectal cancer developed a 1.5 cm LUL pulmonary mass compatible with a metastatic lesion (Figs. 1A&B). He subsequently underwent VATS wedge-resection with chest radiograph (CXR) showing expected post-surgical changes (Fig. 2). The patient returned for follow-up approximately 4 months post-resection. PA and lateral views demonstrated an increased region of irregular opacification surrounding the surgical bed (Figs. 3A&B). He had radiation treatment in the interim.
Radiation pneumonitis is the acute form of radiation-induced lung disease (RILD) following treatment for thoracic malignancies. Chest x-ray findings are nonspecific, but involve airspace opacification, consolidation, or atelectasis confined to the irradiated focus from regional alveolar damage. Pleural effusions may also occur in this setting. The differential diagnosis includes bacterial pneumonia, recurrent tumor, lymphangitic tumor, or drug reaction.
Most patients are asymptomatic, though they may experience dyspnea, cough, fever, or pleuritic pain. Corticosteroids are the standard treatment and sudden withdrawal increases the risk for recurrent radiation pneumonitis.
The acute phase of disease occurs between 4 and 12 weeks following completion of a radiotherapy course, though it may be seen as early as 1 week if high doses are used. The peak acute change is about 4 months post-radiation with dense consolidation of the involved lung. This gradually clears and evolves into a more chronic morphology.
Chronic radiation changes consist of fibrosis, traction bronchiectasis, architectural distortion, cicatricial atelectasis, and scarring about 6-24 months following treatment. After this period, cicatricial atelectasis mostly stabilizes and any further lung changes are likely related to recurrent tumor or infection.
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- Choi YW, Munden RF, Erasmus JJ, et al. Effects of radiation therapy on the lung: radiologic appearances and differential diagnosis. Radiographics. 2004 Jul-Aug;24(4):985-97. PMID: 15256622