# Eosinophilic Gastroenteritis with Appendix Involvement: Role of Intestinal Ultrasound
###### Abstract
The detection of HTLV antibodies, anti-Anisakis IgE, and screening for ANA, ENA, and ANCA tested negative. Serum IgA, IgG, IgM, C3, and C4 were measured and resulted within the normal range. All the infection tests, including stool cultures for bacteria and parasites, were repeated and tested negative, thus excluding any infective causes of hyper-eosinophilia. Therefore, in order to rule out chronic eosinophil leukemia, mutations of FIP1L1-PDGFRA were searched for and tested negative. In the GI ultrasound, the jejun and ileal loops appeared slightly dilated with increased liquid or slightly echoic content (Figure 1). Reactive mildly enlarged mesenteric lymph nodes (maximum diameter 10 \(\times\) 5 mm) were still present. In the right lower quadrant, a thickened hyper-vascularized appendix (maximum diameter: 6.9 mm) was evidenced (Figure 2), surrounded by hypertrophic activated mesentery and a small amount of free abdominal fluid (arrow). The patient ([PERSON]) gave his consent for the publication of information about his case, as contained in the present case report. An ileocolonoscopy was performed and showed a highlighted, white-speckled lesion next to the appendicular orifice. Well-oriented endoscopic biopsies of the whole tracts being explored were collected. An esophagogastroudonoscopy was also performed and showed a macroscopically normal pattern; multiple biopsies were obtained against the suspicion of eosinophil gastroenteritis. Histological examinations showed a remarkable eosinophil infiltration in the duodenal (35-50 eosinophils/HPF), ileo-ecal (60 eosinophils/HPF), and colonic (25-30 eosinophils/HPF) mucosa. These findings confirmed our clinical suspicion of eosinophil gastroenteritis on the basis that, according to the pathologist expertise in our hospital, the diagnostic cut-off values for the diagnosis of EG are as follows: 35-40 eosinophils/HPF in the duodenum, 40 eosinophils/HPF in the ileum-eccum, and 25-30 eosinophils/HPF in the rest of the colon. Figure 1: Transverse real-time ultrasound scan of the bowel performed with a high-frequency transducer (5–12 MHz), showing moderately dilated bowel loops with a slightly thickened bowel wall and increased moderately echoic luminal content. Figure 2: Transverse real-time ultrasound scan of the right lower quadrant performed with a high-frequency transducer (5–12 MHz), showing appendix involvement in EG with thickening of the wall, target sign, diameter >6 mm, hyperemia of the wall, and surrounding free fluid. We prescribed a glucocorticoid regimen based on prednisone 30 mg/die, with the indication of rapid and progressive tapering during the following two weeks. The eosinophilic count rapidly decreased and gastrointestinal symptoms disappeared. The patient was discharged. Gastrointestinal US was repeated at the end of the steroidal therapy, with evidence of a normalized appendicular diameter (5.5 mm), persisting mild hyper-vascularization, and reduction of adjacent free fluid. After 8 weeks from the discontinuation of prednisone, a new US was performed with evidence of complete resolution of the appendicular inflammation and disappearance of all pathological findings (Figure 3a,b). Figure 3: (**a**) Longitudinal and (**b**) transverse real-time ultrasound scan of the right lower quadrant performed with a high-frequency transducer (5-12 MHz), showing the complete resolution of appendicular inflammation with disappearance of any free abdominal fluid. A maintenance therapy with a budesonide-based regimen was prescribed (starting at 9 mg). Good control of symptoms and reduction of the eosinophilic count was achieved, with progressive steroid tapering to 3 mg/day. Because of the chronic adverse effects of steroidal therapy, as particularly observed in long-term therapy, an attempt with ketotifen was chosen and is actually ongoing. The patient is currently symptomless and blood tests, including the eosinophil count, are normal.