S2944 A Rare Disease Caused by Treatment of a Common Problem

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INTRODUCTION: Collagenous gastritis (CG) is a histologic diagnosis that is defined as subepithelial thickening to >10 μm due to the deposition of collagen tissue. It is a rare disease with unclear etiology but has strong association with autoimmune diseases. We present a case of collagenous gastritis induced by Olmesartan. CASE DESCRIPTION/METHODS: A 62- years-old woman with hypertension presented with nausea, epigastric pain, weight loss, and odd-tasting saliva for 1 month. Pertinent physical examination revealed normal vital signs and tenderness of the epigastric area without signs of peritonitis. Workup for all potential infectious causes and celiac disease was negative. An upper endoscopy showed gastritis with umbilications in the antrum and gastric mucosal atrophy in the gastric body and fundus. Gastric histopathology revealed collagenous gastritis with mucosal atrophy and eosinophilic infiltrate without intestinal metaplasia (Figure 1). Duodenal biopsy revealed preserved villi. In light of negative celiac disease and after review of the patient’s medication, the diagnosis of Olmesartan induced collagenous gastritis was considered. Olmesartan was discontinued and her symptoms resolved. Two months later her weight had returned to normal. DISCUSSION: Olmesartan associated collagenous gastritis (OACG) is a rare disease that was initially reported in 2012. In adults, OACG without small and/or large bowel involvement is exceptionally rare. Presenting symptoms are abdominal pain, nausea, vomiting, weight loss, and anemia. Symptoms develop months to years after the initiation of olmesartan therapy. The presumptive diagnosis of OACG is made in patients who develop symptoms while taking olmesartan with a supportive histologic finding on gastrointestinal biopsies. Discontinuation of olmesartan has been the mainstay of treatment.Figure 1.: High power view: Thickened basement membrane (green arrow), and eosinophils (red arrow), lymphoplasmacytic infiltrate (white arrows head).