Feature | UIP of IPF | RILD | CHrHP |
---|---|---|---|
Age | >60 years | Middle-aged | <60 years |
Sex | Male>>>Female | Female>>Male | Female>Male |
Systemic manifestations | Rare | Frequent | Rare |
Smoking history | Frequent | Variable | Uncommon |
Inhalational exposure history (fumes, organic and inorganic dusts) | Uncommon | Inconsistent | Frequent |
Serologic evidence of autoimmunity | Rare | Frequent | Rare |
HRCT fibrosis distribution | Paraseptal and subpleural Lower lobe predominance | Mixed, often basilar | Centrilobular Variable but often in upper and mid-lung zones |
HRCT ground-glass opacities | Usually only focal and in lower lobes near reticulation | Common throughout lung fields | Variable, distributed along bronchovascular bundles |
Fibroblast foci | Frequent and typically at leading edge of confluent fibrosis | Few but similar distribution to UIP in IPF | Rare and inconsistent in location |
Lymphoid hyperplasia | Rare | Frequent, often with germinal centres | Variable |
Smooth muscle proliferation in scar | Common | Uncommon | Sometime, in centrilobular scars |
Follicular bronchiolitis | Rare | Very frequent | Uncommon |
Synchronous acute lung injury and/or organising pneumonia | Rare unless acute exacerbation | Frequent | Common, but as patchy organising pneumonia |
Background NSIP pattern | Rare | Frequent | Variable |
Interstitial granulomas | Absent | Absent | Present |
Peribronchiolar metaplasia | Mild and focal | May be extensive | Extensive |
CHrHP, chronic hypersensitivity pneumonitis; HRCT, high-resolution CT; IPF, idiopathic pulmonary fibrosis; NSIP, non-specific interstitial pneumonia; RILD, rheumatic interstitial lung disease; UIP, usual interstitial pneumonia.