The significance of antineutrophil cytoplasmic antibody in microscopic polyangitis and classic polyarteritis nodosa

Aims-To describe the distribution and features of classic polyarteritis nod osa (PAN) and microscopic polyarteritis (MPA) and the importance of antineu trophil cytoplasmic antibody (ANCA) in childhood PAN. Methods-Classic PAN was diagnosed in 15 patients based on the presence of a neurysms on angiography in 10 patients and of necrotising vasculitis in med ium sized arteries in five. NIPA was diagnosed in 10 patients, based on cha racteristic findings at renal biopsy in six and by the presence of small si zed necrotising arteritis in four. Serum ANCA was detected initially by ind irect immunofluorescence (IIF) followed by an immunoassay for myeloperoxida se (MPO) in each case. Results-The median age of the patients with classic PAN and MPA was 12 (ran ge 8-17) and 9.5 (range 5-14) respectively. None of the patients with class ic PAN had renal failure. Six of the patients with MPA presented with renal failure; four progressed to chronic renal failure. Clinically evident pulm onary renal syndrome was present in three of the 10 patients with NIPA. IIF for ANCA in classic PAN was negative in nine, showed mild staining pattern s in six, and in one MPO-ELISA was mildly increased. IIF for ANCA in NIPA r evealed very strong perinuclear ANCA staining in nine and atypical staining in one. In NIPA, median MPO-ELISA level was 42.5 EU/ml (range 20-250). Tre atment of childhood PAN was satisfactory with effective treatment; however relapses did occur. Conclusion-ANCA is useful in the diagnosis and follow up of MPA.