A case of Polyarteritis Nodosa Mimicking Pyelonephritis and was Misdiagnosed as Inflammatory Bowel Disease

Polyarteritis nodosa (PAN) is characterized by necrotizing inflammation of small- or medium-sized muscular arteries. Atypic clinical presentation leads to delay in diagnosis. For this reason, it can cause severe morbidity and mortality. Here, we described a case which presented first with fever and left costovertebral angle tenderness, and was misdiagnosed as pyelonephritis. The patient did not benefit from intravenous antibiotherapy that was prescribed in the outpatient clinic and then hospitalized for left lower abdominal pain. No source of fever was found despite detailed physical examination and laboratory investigation. An abdominal ultrasonography showed hyperechogenity of the left kidney. An abdominal computed tomography was performed for left lower abdominal pain suggesting inflammatory bowel disease findings. Colonoscopy showed an ulcero-vegetating and nodular mass surrounding the whole sigmoid colon mucosa and suggesting a malignant tumour. A conventional angiography of the mesenteric artery showed total occlusion of the inferior mesenteric artery. He developed acute abdominal pain and, left hemicolectomy was performed for colonic perforation. Histopathological findings consistent with PAN were detected in the pathological examination of the resected bowel, and the patient was diagnosed with PAN. After initiation of corticosteroid and cyclophosphamide therapy, the clinical status of the patient was improved dramatically with disappearence of fever and relief of abdominal pain. Turk J Phys Med Rehab 2013;59:79-82.