Anti-neutrophil cytoplasmic antibody for proteinase 3 in a child with polyarteritis nodosa.

We report a case of a 15 year old boy with polyarteritis nodosa associated with antineutrophil cytoplasmic antibody (ANCA) against proteinase 3 (PR3). After months of steroid and immunosuppressant therapy, the symptoms subsided and the polyaneurysms almost disappeared. The levels of anti-PR3 antibody and of cytokines also decreased. The results indicate that ANCA is a good indicator of this disease activity, and may play some pathogenic role in the disease.