RESUMEN
Objective To understand the clinical characteristics of primary small vessel vasculitis with involvement of lungs in children and analyze the causes of misdiagnosis.Methods Clinical data from 16 patients with primary small vessel vasculitis were collected and their pathological,antineutrophil cytoplasmic antibody(ANCA),pulmonary lesion manifestations,image and misdiagnosis were further analyzed.Results Among 16 cases,9 cases were microscopic polyarateritis(MPA) and 4 cases were Wegeners granulomatosis(WG) and 3 cases were Churg-Strause syndrome(CSS).The ages of onset were from 3 to 14 years old with average age of 7.5 years old.Seventy-five percent(12/16) were ANCA positive.The patients with lung involvement had cough,chest pain,dyspnea,hemoptasis and asthma.Findings on lung X-ray films were variable.Some showed multiple patch shadows,others showed single or multiple masses or nodular shadows with or without cavity formation.After the treatments with corticosteroid and cyclophosphamide,10 cases turned better;including 8 cases with normal on lung X-ray films.Three cases given up;3 cases died.Conclusion It is very difficult to make diagnosis of primary small vessel vasculitis with involvement of lungs and should be paid more attentions to this issue.