Diffuse Alveolar Hemorrhage in Systemic Lupus Erythematosus: Histopathologic Features and Clinical Correlations

Figure 4

Lung with diffuse alveolar hemorrhage (H&E stain). (a) Area in which all alveoli are filled with extravasated erythrocytes. (b) Higher power view of same region. Note the hypercellularity of the alveolar septa. (c) A mixture of red cells and fibrin predominates in some alveoli (arrows). (d) The central alveolus contains a fibrin plug (asterisk). The alveolar septum is hypercellular. (e) The alveolar septum shows capillaritis (arrows), an inflammatory infiltrate containing neutrophils that degenerate releasing toxic compounds, causing capillary injury and leakage of erythrocytes. (f) High power view of septum with capillaritis. (g) A hyaline membrane abuts a damaged alveolar septum. (h) There were occasional foci of small vessel vasculitis (arrows).

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