2655 A Unique Case of Polyarteritis Nodosa Involving the Gastrointestinal Tract

Abstract

INTRODUCTION: Polyarteritis nodosa (PAN) is a rare, systemic necrotizing vasculitis that affects medium-sized arteries and leads to inflammation resulting in vessel narrowing, thrombosis, and aneurysms. It can involve multiple organs and therefore presents with a range of non-specific symptoms. Gastrointestinal (GI) involvement of PAN is uncommon and may manifest as abdominal pain and rectal bleeding. Herein we describe an unusual case of PAN involving the small bowel in a patient presenting with abdominal pain. CASE DESCRIPTION/METHODS: A 49 year old man presented with acute onset left upper quadrant abdominal pain associated with nausea, vomiting, constipation, and multiple episodes of rectal bleeding. Vitals were unremarkable. Physical exam notable for abdominal tenderness and external hemorrhoids. Lab work revealed WBC 25, hemoglobin 11.6, platelets 476, and BMP unremarkable. Autoimmune markers revealed CRP 200, ESR 76, and ANA, ASMA, p-ANCA, c-ANCA, and acute hepatitis panel was negative. CT revealed splenic infarcts with no evidence of acute bowel ischemia. Arteriogram revealed multiple abnormalities including focal narrowing and irregularities of renal artery, distal splenic artery, as well as ileal and jejunal arteries (Figure 1a). Small bowel enteroscopy revealed jejunal erosions with biopsies showing focal erosive jejunitis and small caliber arteries without evidence of vasculitis. Colonoscopy positive only for large external hemorrhoids. Video capsule identified partial loss of villi, mucosal flattening, and multiple areas of ulceration throughout the small bowel (Figure 2) concerning for ischemia. Due to the high degree of concern for PAN with small bowel involvement, high dose prednisone and cyclophosphamide were initiated with improvement of symptoms. Follow-up angiogram revealed improvement in previous focal narrowing and segmental stenosis (Figure 1b). DISCUSSION: Diagnosing PAN is challenging and involves biopsy of an affected organ to identify medium-sized artery vasculitis. As in this case, establishing PAN with GI involvement is difficult due to the low likelihood of identifying medium-sized artery vasculitis on endoscopic biopsy of the GI tract. Invasive small bowel resection is oftentimes unrealistic. Untreated PAN can lead to devastating outcomes including ischemia of multiple organs as ongoing inflammation of vessels results in progressive narrowing. Thus, consideration should be given to initiating aggressive therapy based on imaging findings and clinical presentation if GI-PAN is suspected.