[Clinical thinking and decision-making in practice. A patient with arthritis, skin lesions and a perforated nasal septum].

A man aged 38 years had arthritis, skin lesions and a perforation of the nasal septum. He had slight deterioration of renal function and a few granular casts in the urine. Antineutrophil cytoplasmic antibody and other immune parameters were normal. A biopsy of the nasal septum did not show granulomatous lesions. The differential diagnosis on the available clinical grounds could be narrowed to Wegener's disease, Henoch-Schönlein vasculitis or microscopic polyangiitis. A biopsy of the skin showed leukocytoclastic vasculitis, with IgA and IgM depositions compatible with Henoch-Schönlein vasculitis. A renal biopsy showed small segmental necrotising lesions of the glomerular capillaries, with minimal extracapillary proliferation; immune fluorescence did not detect any significant depositions. The picture was compatible with Wegener's disease. A nasal septum defect together with glomerulonephritis, which could be suspected from only minimal abnormalities in the urine, is almost conclusive for the diagnosis.