[Gastrointestinal involvement and renal infarction in a boy with classic polyarteritis nodosa diagnosed with 3D-computed tomography angiography].

We report a case of classic polyarteritis nodosa complicated with renal infarction. A 14-year-old boy manifested fever, abdominal pain, watery and bloody diarrhea, and weight loss. Laboratory findings indicated anemia, increased levels of C-reactive protein, and erythrocyte sedimentation rate. Lower gastrointestinal endoscopic examination revealed multiple colorectal ulcerations, and histopathological findings were non-specific, suggesting gastrointestinal involvement of Behcet disease. The patient was referred to our hospital, and suspected to have vasculitis syndrome since the abnormal laboratory findings included persistently increased levels of FDP-E/fibrin monomer as well as inflammatory markers, and the extraordinary high excretion of beta 2-microglobulin, which indicated abrupt and massive expression of HLA class I molecule on endothelial cells due to interferon-gammanemia. To examine the site of vasculitis, 3D-CT angiography was applied to demonstrate bilateral renal infarction and renal artery microaneurysms. Together with the clinical, laboratory, and 3D-CT angiographic findings, he was finally diagnosed as having classic polyarteritis nodosa. After 12 month-course of intravenous cyclophosphamide pulses and prednisolone/azatioprine therapy, complete disappearances of inflammatory manifestations, and renal infarction and microaneurysms were documented. The diagnosis of classic polyarteritis nodosa is frequently delayed because both clinical symptoms and signs, and laboratory findings are not disease-specific, but early diagnosis and treatment are necessary to prevent serious organ damage. In addition to the precise estimation of laboratory findings such as inflammatory markers, and FDP-E/D-dimer/fibrin monomer, the newly developed 3D-CT angiography, a less invasive imaging technique, will be helpful to diagnose patients with classic polyarteritis nodosa, and intervene the disease progression with early and active treatment.