# Eosinophilic Colitis as a Rare Etiology of Chronic Diarrhea: A Case Report

## TL;DR

This case report describes a rare condition called eosinophilic colitis in a 67-year-old woman with chronic diarrhea, highlighting the diagnostic and treatment challenges.

## Contribution

The paper presents a new case of eosinophilic colitis and emphasizes the role of corticosteroids and antihistamines in treatment.

## Key findings

- The patient showed clinical improvement after treatment with corticosteroids and antihistamines.
- Endoscopy was crucial in diagnosing the condition despite normal macroscopic findings.
- EC remains a diagnosis of exclusion due to lack of standardized diagnostic criteria.

## Abstract

Eosinophilic colitis (EC) is a rare condition associated with abnormal infiltration of the colonic mucosa by eosinophilic polymorphonuclear cells (EPS). The clinical picture in adults with EC is varied and nonspecific, with the most common symptoms being diarrhea and abdominal pain. Although the etiology of primary colonic eosinophilia is unknown, several criteria are involved in the pathogenesis of secondary eosinophilic colonic infiltration (parasitic infections, drugs, and food allergens), which must be excluded to diagnose the primary form of the disease correctly. The diagnosis of EC currently poses a major problem due to the lack of consensus on histological diagnostic criteria for the disease and on the physiological levels of eosinophils (EPS) in normal colonic mucosa. Endoscopy, imaging, and laboratory tests may be useful in ruling out other similar conditions, but EC remains a diagnosis of exclusion. Several treatment options are available, but most of the evidence comes from case reports and small case series, which limits their value. We report here the case of EC in a 67-year-old female patient, which was revealed during an etiological evaluation of chronic diarrhea. Endoscopy revealed a normal macroscopic appearance of the mucosa of the stomach, duodenum, terminal ileum, and colon. The patient was treated with systemic corticosteroids and antihistamines, with good clinical progress, and the episodes of diarrhea decreased after one week. This case highlights the value of treatment with oral corticosteroids and antihistamines and also reminds us of the important role of endoscopy in the etiological diagnosis of chronic diarrhea.