Pulmonary capillaritis and its relationship to development of emphysema in hypocomplementaemic urticarial vasculitis syndrome.

Hypocomplementaemic urticarial vasculitis syndrome (HUVS) is a rare disorder characterised by complement activation and the presence of C1q precipitins together with a syndrome of urticarial vasculitis, angioedema, arthralgia, ocular inflammation, glomerulonephritis and obstructive lung disease. The pathophysiology of the obstructive airways disease is poorly understood. We report a 46 year-old woman with HUVS who developed progressive obstructive airways disease. Lung biopsy early in the course of her disease revealed pulmonary capillaritis. The disease progressed despite treatment with steroids and cyclosporin and the patient eventually underwent successful double lung transplantation. The explanted lung showed the coexistence of a patchy active vasculitis with severe panacinar emphysema. This is the first description of the histopathological process of HUVS in an explanted lung. Through analysis of serial histopathological specimens and clinical data we show the evolution of pulmonary capillaritis to emphysema, and demonstrate that active vasculitis can coexist with emphysema in patients with HUVS and obstructive airways disease. We suggest that there is a role for ongoing immunosuppressive therapy in these patients.