Causes of Interstitial Lung Disease - Differential Diagnosis Algorithm

Idiopathic Interstitial Pneumonia

 • (UIP) Usual Interstitial Pneumonia - fibrosis, with relatively little inflammation, most common   

 • (NSIP) Non-specific Interstitial Pneumonia  

 • (DIP) Desquamative Intersitial Pneumonia  

 • (LIP) Lymphoid Interstitial Pneumonia - slowly progressive dyspnea and cough, “velcro” crackles, clubbing, worse at the bases and periphery, Poor Prognosis  

Granulomatous - Sarcoidosis (Debate if this should be 1° or 2°) - Multisystem characterized by granulomatous inflammation 

Primary - Other (Rare)

 • Lymphangioleiomyomatosis (LAM),  

 • Pulmonary Langerhans cell histiocytosis (PLCH)  

 • Eosinophilic pneumonia

Congestive Heart Failure - Impaired cardiac function resulting in fluid leaking out of pulmonary capillaries into intersitial space

Infection - “Atypical” Pneumonia

Malignancy - Metastases to lung as nodules 

Hypersensitivity Pneumonia - Immunologic (hypersensitivity) reaction to inhaled antigen 

Connective Tissue Disease - Rheumatoid Arthritis, Systemic Lupus and Scleroderma 

Pneumonconiosis - Lung disease (nonneoplastic) resulting from inhalation of inorganic and organic dusts 

Drugs/Radiaition

 • Drugs: Amiodarone, Nitrofurantoin, Methotrexate, Beomycin

 • Acute or Chronic Radiation Pneumonitis - 4-12 weeks after exposure, 6-12 after.



- Amy Chung, MD, MSc @AmyChung 



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