Hypersensitivity vasculitis of the duodenum.

Abstract

A 43-year-old woman taking captopril for hypertension had abdominal pain, nausea, guaiac-positive diarrhea, and a pruritic maculopapular rash. An adominal CT scan (Fig. 1A) showed marked thickening of the walls of the duodenum, segments of small bowel, and sigmoid colon. Stranding of the mesenteric fat and a small amount of ascites were noted. An MR angiogram (Fig. 1B) showed a patent celiac artery with widely patent celiac branches and a normal superior mesenteric artery. Results of an endoscopic duodenal biopsy revealed evidence of ischemia, fragmentation of white blood cells (leukocytoclasis), and fibrinoid necrosis of the walls of small blood vessels (Fig. 1C). The final pathologic diagnosis was hypersensitivity (leukocytoclastic) vasculitis involving superficial and deep mucosal blood vessels. Three days after captopnil was discontinued, the patient’s rash and abdominal pain ended. Findings on an abdominal CT scan, obtained 8 days after the first CT, were normal. Hypersensitivity vasculitis involves inflammation of the small blood vessels (arterioles, capillaries, and venules). Hypersensitivity vasculitis is believed to be an allergic response to a precipitating antigen, such as a drug, a vaccine, a microorganism, or a foreign protein [1]. Immune complexes are deposited in the walls of small vessels, activating the complement cascade. Polymorphonuclear leukocytes infiltrate the vessel walls and release lysosomal enzymes. This damage results in fibrin deposition and necrosis [1]. Most patients with hypersensitivity vasculitis have palpable purpura or a maculopapular rash [2]. Approximately 30% of patients have adominal pain or gastrointestinal bleeding [2, 3]. In patients with hypersensitivity vasculitis, plain radiographs may show thumbpninting of the bowel wall, and barium studies may reveal mucosal edema [2]. CT scans may show multiple segments of bowel with thickened walls. Findings on conventional and MR angiograms are often normal because only small vessels are involved. Definitive diagnosis of hypersensitivity vasculitis requires a biopsy (usually ofthe skin) [1]. Treatment consists of elimination of any potential etiologic antigen, although in many cases no specific antigen is identified. If involvement of internal organs or severe skin involvement occurs, prednisone or cyclophosphamide may be used [4]. Most cases resolve completely, and life-threatening intestinal complications are rare [5].