S6439 The Diagnosis of Eosinophilic Gastritis and Hypereosinophilic Syndrome

Introduction: Eosinophilic gastritis is a rare disorder with evidence of endothelial injury and eosinophilic infiltrates within the lamina propria. It is seen in 6.3/100,000 people and presents in patients 20 to 50 years old with nonspecific symptoms such as abdominal pain, nausea, vomiting and malabsorption. There are no definitive standards for diagnosis; however, findings supportive of diagnosis include elevated eosinophils on biopsy with >30 eosinophils per/high power field in gastric glands, lack of other organ involvement and exclusion of other causes of eosinophilia. Case Description/Methods: A 33-year-old woman with a past history of anorexia nervosa and constipation predominant irritable bowel syndrome (IBS) presenting with new concerns of diarrhea with nighttime awakenings, lower abdominal pain, and nausea. She had a prior esophagogastroduodenoscopy (EGD) completed in 2016 which was consistent with findings for Celiac disease, although she did not complete serologic testing. A complete blood count was obtained and pertinent for an absolute eosinophil count (AEC) of 2428 (normal 15-500 cells/uL). The patient initiated a gluten free diet without symptom resolution. She subsequently underwent repeat EGD, confirming Celiac disease as well as gastric mucosa with focal increased density of eosinophils up to 100/hpf. She was initiated on mepolizumab with improvement in her diffuse pain and resolution of AEC to 101. Discussion: This patient presented with new onset diarrhea and abdominal pain with a history of constipation and anorexia nervosa. She was found to have significant peripheral eosinophilia. Upon further negative workup, hypereosinophilic syndrome (HES) was proposed although there was no apparent tissue damage required for diagnosis. Due to her GI symptoms, an EGD was performed. Gastric biopsies showed >100 eosinophils/hpf confirming tissue damage and a diagnosis of HES, but also identifying a rare eosinophilic gastritis diagnosis. It was critical to identify a change in symptoms from the patient’s baseline as well as avoiding anchoring on prior diagnoses like IBS, anorexia, and Celiac disease to reach the diagnosis of HES and eosinophilic gastritis. It is important to consider that greater than one diagnosis may be driving a patient's presentation, especially when an underlying functional GI condition has been diagnosed and there is a change in the frequency, severity or quality of symptoms. This case highlights the importance of maintaining a broad differential diagnosis when a change in symptoms develops.