Diffuse alveolar hemorrhage
- Lesion
Bleeding into many alveoli at once, from autoimmune attack on the basement membrane or from capillaritis. It shows as hemoptysis, anaemia and hemosiderin.
What it is
Diffuse pulmonary hemorrhage syndromes flood the alveoli with blood. Three groups matter: anti-glomerular basement membrane disease with lung involvement (Goodpasture syndrome), vasculitis-associated hemorrhage (granulomatosis with polyangiitis, microscopic polyangiitis, lupus) and idiopathic pulmonary hemosiderosis. Pulmonary-renal syndromes (lung hemorrhage plus rapidly progressive glomerulonephritis) are emergencies.
Structure
- Gross: heavy lungs with red-brown consolidation.
- H&E: blood in alveoli, focal necrosis of alveolar walls, many hemosiderin-laden macrophages; later septal fibrosis and type II hyperplasia.
- Immunofluorescence (Goodpasture): linear IgG and complement along basement membranes.
- GPA: neutrophilic capillaritis, necrotising vasculitis, geographic necrosis and poorly formed granulomas with giant cells.
Step by step
- Autoantibodies (anti-GBM) or ANCA-activated neutrophils attack the alveolar capillary wall.
- In Goodpasture, smoke or infection may expose the hidden collagen epitope in the lung.
- Complement and neutrophils destroy the capillaries (capillaritis) and the basement membrane.
- Red cells pour into the alveoli; macrophages ingest them and convert haem iron to hemosiderin.
- The same attack in glomeruli causes crescentic glomerulonephritis.
- Repeated episodes leave fibrosis and iron deficiency.
Causes of diffuse alveolar hemorrhage
| Disease | Antibody | Immunofluorescence | Other clues |
|---|---|---|---|
| Anti-GBM (Goodpasture) | Anti-α3 type IV collagen | Linear IgG | Young male smokers, renal failure |
| Granulomatosis with polyangiitis | PR3-ANCA | Pauci-immune | Sinusitis, nasal destruction, granulomas |
| Microscopic polyangiitis | MPO-ANCA | Pauci-immune | No granulomas |
| Systemic lupus erythematosus | ANA, anti-dsDNA | Granular immune complexes | Other lupus features |
| Idiopathic pulmonary hemosiderosis | None | Negative | Young children, anaemia |
Markers
- Prussian blue
- Linear IgG
- PR3-ANCA
- MPO-ANCA
Clinical notes
- Hemoptysis (sometimes absent despite major bleeding), falling haemoglobin, new bilateral infiltrates, rising DLCO.
- Check urine sediment and creatinine; test anti-GBM and ANCA.
- Treatment: plasma exchange (anti-GBM) and immunosuppression; outcomes improve with early diagnosis.
Test yourself
Think of the answer, then tap the question to see it.
What is the target antigen in Goodpasture syndrome?
The noncollagenous domain of the α3 chain of type IV collagen in glomerular and alveolar basement membranes.
What immunofluorescence pattern does anti-GBM disease show?
Linear deposits of IgG (and complement) along the basement membranes.
Which cells prove repeated alveolar bleeding, and how are they shown?
Hemosiderin-laden macrophages, highlighted blue by the Prussian blue iron stain.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Lung Diseases (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.