[A child case of idiopathic membranous glomerulonephritis associated with isolated anti-nuclear antibody detected by urine mass-screening of school children].

: A 12-year-old boy was referred to our hospital because of persistent hematuria with proteinuria. He was found to have urine abnormalities by a school mass-screening and visited a hospital, where a routine examination revealed proteinuria of 190 mg/d/, hematuria of 2+ and anti-nuclear antibody (ANA) of 1: 320 with a speckled pattern. The other laboratory findings, including anti-DNA antibody were unremarkable. Hypocomplementemia was not seen. Although he had no disabilities and manifestations suggesting systemic lupus erythematosus, urine abnormalities persisted. Percutaneous renal biopsy findings demonstrated stage II diffuse membranous glomerulonephritis (MGN). Neither anti-hepatitis B virus antigens and antibodies nor hepatitis C virus antibody were detected in his sera. Thus, the diagnosis of idiopathic MGN was made. Initiation of a 6-month course of alternate-day prednisolone (an initial dosage at 30 mg) combined with an anti-thrombocyte agent resulted in gradual subsidence of the urine abnormalities and ANA titer. Although pathogenesis of his MGN remains speculative, possible activation of autoimmunities, which led to ANA positivity, might be responsible.