Desquamative Interstitial Pneumonia

Definition

Clinical
- Nearly all affected patients are smokers
  - Adults, average age 30-60
- Generally subacute dyspnea, cough
- Good response to steroids and smoking cessation
  - 70% 10 year survival
High resolution computed tomography (HRCT)
- Bilateral ground glass opacities
  - Lower lung fields
  - May be peripheral and patchy
Histopathologic features
- Diffuse, uniform expansion and filling of alveoli and distal airways by macrophages
  - Macrophages contain finely granular golden brown pigment
    - Iron positive
    - Termed "smokers macrophages"
- Mild to moderate fibrotic thickening of alveolar septa
  - Architecture is preserved
  - No scarring or honeycomb change
  - Fibroblastic foci rare
- Mild interstitial infiltrate of plasma cells and lymphocytes
  - Lymphoid follicles frequently present but scattered
  - Eosinophils frequently present but sparse, neutrophils absent
- Alveoli lined by reactive alveolar lining cells
- Occurring in smokers' lungs, other clinicopathologic disorders such as chronic bronchitis and emphysema are frequently present
- The following features should not be seen
May form a spectrum with respiratory bronchiolitis associated interstitial lung disease
- Patchy (RBAILD) vs. diffuse (DIP) airspace involvement by macrophages
Similar infiltrates may be seen adjacent to tumors and scars

Gerald J Berry MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 11/20/10; 8/13/11, 12/29/12