Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH)

DAH is associated with many different conditions. Many, like Wegener's granulomatosis (WG), have a capillaritis. WG, however, shows no electron dense deposits or immunofluorescent staining.

Two other types of lesions are shown below.

This photo shows RBCs (red) and proteinaceous exudate (pink) in alveolar spaces. The alveolar walls have increased numbers of inflammatory cells including PMNs (capillaritis). An iron stain will show hemosiderin-filled macrophages about 2 days after the bleed.

In systemic lupus erythematosus, DAH is associated with focal, electron dense deposits in the alveolar-capillary basement membrane (arrow). A type I cell lies to the right of the tip of the arrow and the endothelial cell lies to the left. The asterisk marks the capillary lumen.

At higher magnification, the electron dense deposit shows a layered, "fingerprint" pattern (best seen at the arrow). These deposits account for a "lumpy-bumpy," discontinuous pattern seen by immunofluorescence.

DAH in Goodpasture's syndrome is accompanied by a linear immunofluorescence seen at the arrow. Ultrastructurally, deposits are absent.

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