American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the hallmark sign of eosinophilic esophagitis on histologic analysis?

1. Presence of neutrophils

2. Presence of eosinophils

3. Presence of lymphocytes

4. Presence of basophils

The correct answer is: Presence of eosinophils

The hallmark sign of eosinophilic esophagitis on histologic analysis is the presence of eosinophils. Eosinophilic esophagitis is an inflammatory condition of the esophagus characterized primarily by accumulated eosinophils in the esophageal epithelium. These cells are a type of white blood cell that typically respond to allergens, parasitic infections, and certain autoimmune conditions. In this condition, the infiltrating eosinophils contribute to the inflammation and tissue damage seen in affected patients, leading to symptoms such as dysphagia and food impaction. While neutrophils, lymphocytes, and basophils can be present in various inflammatory conditions, their presence is not characteristic of eosinophilic esophagitis. Neutrophils are more associated with acute inflammation and infection, lymphocytes are often involved in chronic inflammatory responses or in diseases like lymphocytic esophagitis, and basophils are typically involved in allergic reactions and parasitic infections but are not a defining feature of this particular esophageal condition. Therefore, the identification of eosinophils in histologic samples is key to diagnosing eosinophilic esophagitis.