Eosinophilic Colitis in an Adult Patient: A Case Report.

Eosinophilic colitis (EC) is a rare inflammatory condition that often mimics irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD), making it difficult to diagnose. It is characterized by significant eosinophilic infiltration in the colon, leading to symptoms like abdominal pain, diarrhea, and constipation. Herein, we present the case of a 43-year-old woman struggling with severe, episodic abdominal pain and unpredictable bowel habits, whose colonoscopy appeared grossly normal. Yet, mucosal biopsies revealed severe eosinophilic infiltration (>100 eosinophils per high-power field) in the cecum and ascending colon, with significant eosinophilia also noted in the transverse colon. These findings confirmed the diagnosis of eosinophilic colitis. This case underscores the rare but important presentation of EC with endoscopically normal mucosa and highlights how biopsy can be the only clue to an otherwise elusive diagnosis.