Return to case

Radiation Pneumonitis 

• Damage to lungs after radiation therapy
• Usually requires at least 4500 rads
  • Especially common if >6000 R given in 5-6 weeks
• Occurs more often if there is concurrent or later chemotherapy
• Pathologic phases
  • Exudative phase = edema fluid + hyaline membranes
  • Organizing phase
  • Fibrotic phase = interstitial fibrosis
• Time of onset
  • Usually at least 6 weeks up to 6 months after treatment
• Location
  • Confined to radiation portal

 

Radiation portal (left) with subsequent radiation pneumonitis

·       Acute Radiation Pneumonitis

o       Occurs within 1-8 weeks after radiation therapy

o       Pathology

§         Depletion of surfactant (1 week to 1 month later), plasma exudation, desquamation of alveolar + bronchial cells

o       Usually asymptomatic

o       When symptomatic

§         Nonproductive cough, shortness of breath, weakness, fever (insidious onset)

§         Acute respiratory failure (rare)

o       Changes usually confined to radiation portal

o       Patchy / confluent consolidation, may persist up to 1 month (exudative reaction)

§         Atelectasis + air bronchogram

§         Spontaneous pneumothorax (rare)

• CT findings of acute radiation pneumonitis
  • Homogeneous slight increase in attenuation (2-4 months after therapy)
  • Patchy consolidation (1-12 months after therapy)
  • Non-uniform discrete consolidation (most common; 3 months to 10 years after therapy)

 

Sequential transverse images through lung showing radiation pneumonitis in right lung 

• Prognosis
  • Recovery or progression to death from fibrosis
• Rx
  • Steroids

·       Chronic Radiation Damage

o       9-12 months after radiation therapy

o       Histology

§         Permanent damage of endothelial + type I alveolar cells

o       May be associated with:

§         Thymic cyst

§         Calcified lymph nodes (in Hodgkin disease)

§         Pericarditis + effusion (within 3 years)

§         Severe loss of volume

§         Dense fibrous strands from hilum to periphery

§         Thickening of pleura

o       CT findings

§         Solid consolidation (radiation fibrosis) + bronchiectasis (stabilized by 1 year after therapy)
 

Text from Dahnert, 4^th Edition