Eosinophilic-Crohn overlap colitis and review of the literature

Eosinophilic colitis is an idiopathic inflammation of the alimentary canal and is characterized by infiltration of the intestinal wall by eosinophils, massive submucosal edema, and peripheral eosinophilia. However, the presence of eosinophils in a colon biopsy requires thorough searching for secondary causes and eosinophilic colitis remains a diagnosis of exclusion. A 67-year-old male patient underwent a diagnostic ileocolonoscopy because of recurrent episodes of diarrhea for the last six months. Colonoscopy revealed a normal terminal ileum while in the entire colon an erythematous mucosa with very slight edema on a continuous pattern that was more pronounced in the left colon. The laboratory workup demonstrated eosinophils slightly elevated, biochemical tests were unremarkable and further clinical and laboratory workup was unremarkable. Histology showed overlapping findings of eosinophilic colitis and Crohn's colitis. Patient started on mesalazine 2.4 with very good results. A review of the literature shows that the spectrum of eosinophil involvement in inflammatory bowel disease as well as in eosinophilic colitis is largely varying, including also some exceptional cases that parallel the case described herein.