Polyarteritis nodosa: a case report of isolated large bowel involvement and surgical intervention.

Polyarteritis nodosa (PAN) is a necrotizing vasculitis commonly affecting small-sized vessels and medium-sized vessels. We present the case of surgical resection for ischemic colitis secondary to PAN. A 26-year-old woman presented with left lower quadrant pain, diarrhea and bloody stools. Colonoscopy showed diffuse circumferential ulceration and necrotic lining from the sigmoid colon to the splenic flexure. A subsequent computed tomography angiography (CTA) revealed left colonic wall thickening, hypoenhancement and multiple inferior mesenteric artery aneurysms, concerning for vasculitis. Ensuing laboratory workup all returned negative. Worsening pain, left-sided peritonitis, tachycardia and rising white blood cell necessitated a colectomy from the proximal descending to upper rectum with an end colostomy. Surgical pathology showed features consistent with PAN. The patient improved significantly after surgery and was discharged on a steroid taper and later started on mycophenolate mofetil. This case is a unique presentation of isolated large intestinal involvement and was treated with both medical and surgical interventions.