Usual Interstitial Pneumonia
Differential Diagnosis
Infection must be ruled out in every case
Usual Interstitial Pneumonia |
Acute Interstitial Pneumonia |
Temporal heterogeneity |
Temporally uniform |
Honeycomb change prominent |
Honeycomb change only in late stage |
Patchy distribution with subpleural accentuation |
Diffuse, uniform throughout |
Hyaline membranes not seen |
Hyaline membranes prominent in early stage |
Usual Interstitial Pneumonia |
Desquamative Interstitial Pneumonia |
Intra-alveolar macrophages only focally present |
Diffuse intra-alveolar macrophages |
Temporal heterogeneity |
Temporally uniform |
Architecture destroyed, honeycomb change prominent |
Architecture preserved, honeycomb change uncommon |
Fibroblastic foci common |
Fibroblastic foci absent |
Interstitial fibrosis marked |
Interstitial fibrosis mild to moderate |
Interstitial fibrosis variably distributed |
Interstitial fibrosis tends to be more uniform |
Usual Interstitial Pneumonia |
Cryptogenic Organizing Pneumonia |
Temporal heterogeneity |
Temporally uniform |
Honeycomb change prominent |
Honeycomb change rare |
Interstitial fibrosing process |
Intralumenal fibrosing process |
Fibroblastic foci adjacent to mature collagen, covered by epithelium |
Granulation tissue foci without significant collagen, not subepithelial |
Random distribution |
Bronchiolocentric distribution |
Predominantly collagenous fibrosis |
Predominantly fibroblastic fibrosis |
Organizing pneumonia may be seen focally in UIP or in the setting of acute exacerbation of UIP
- Areas of chronic hypersensitivity pneumonitis may be identical to UIP
- Identification of any of these features should prompt efforts to identify an allergen
- Multiple biopsy specimens may be required
Langerhans Cell Histiocytosis |
Usual Interstitial Pneumonia |
Scars frequently stellate and centrilobular with extension to subpleura |
Irregular subpleural scarring |
Honeycomb change only occasionally seen |
Honeycomb change frequent |
Frequently some typical active LCH lesions present |
Lacks peribronchiolar nodules of Langerhans cells |
Langerhans cells are positive for CD1a and langerin |
CD1a and langerin negative |
HRCT shows centrilobular nodule and cyst pattern |
HRCT shows honeycombing, peripheral accentuation |