Capillaritis

Capillaritis is characterized by focal thickening of alveolar walls, alveolar wall PMNs and karyorrhectic debris, fibrinoid necrosis of the alveolar wall, and interstitial and alveolar blood, fibrin, and hemosiderin. There may be adjacent hyaline membranes or type II cell hyperplasia. The lesion has a variety of different causes and must be suspected in all cases of pulmonary hemorrhage. Changes may be subtle and are often missed [1-3]. A later stage, which is non-specific, shows formation of organizing alveolar polyps attached to the sites of previous hemorrhage. These are composed of fibrinous exudate in the early stages and granulation tissue in later stages. Patients with this lesion may present with hemoptysis &/or anemia and have diffuse, low density radiographic opacities. It is now recognized that this lesion is part of the spectrum of WG, although not specific for it. In patients with diffuse alveolar hemorrhage, the course is often fulminant (acute mortality 66%) [4,5].

In our patient, the CT scan of the upper lobes shows diffuse, bilateral, ground-glass opacities consistent with alveolar hemorrhage.

At the edge of the consolidated area, capillaritis, alveolar exudate, and hemorrhage are present. Many alveolar walls and some air spaces are still visible around the exudate. This pattern is one cause of radiographic ground-glass opacity.

At higher magnification, this focus of capillaritis shows a homogeneous pink, fibrinoid necrosis of the alveolar wall with scattered PMNs and an attached polyp of fibrinous exudate, PMNs, and RBCs in the alveolar space (arrow). Extensive capillaritis, as shown above, may precede the granulomatous consolidation.

Capillaritis from another patient.

Numerous PMNs, some fragmenting, surround these small vessels and widen the alveolar walls. In some places the alveolar epithelium may be eroded (arrow) and in others, there is type II cell hyperplasia. Find some.

Summary of Histologic Features of Capillaritis [4] (Not all need to be present.)

References

1. Myers J, Katzenstein A-L. Wegener's granulomatosis presenting with massive pulmonary hemorrhage and capillaritis. Am J Surg Pathol 1987; 11:895-898.

2. Travis W, Carpenter H, Lie J. Diffuse pulmonary hemorrhage. An uncommon manifestation of Wegener's granulomatosis. Am J Surg Pathol 1987; 11:702-708.

3. Travis W, Colby T, Lombard C, Carpenter H. A clinicopathologic study of 34 cases of diffuse pulmonary hemorrhage with lung biopsy confirmation. Am J Surg Pathol 1990; 14:1112-1125.

4. Green R, Ruoss S, Kraft S, Berry G, Raffin T. Pulmonary capillaritis and alveolar hemorrhage. Update on diagnosis and management. Chest 1996; 110:1305-1316.

5. Sanchez-Masiques J, Ettensohn D. Case report: alveolar hemorrhage in Wegener's granulomatosis. Am J Med Sci 1989; 297:390-393.

Clinical summary Discussion

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