A Case of Amoxicillin-Induced Drug Reaction With Eosinophilia and Systemic Symptoms (Dress) Syndrome Associated With Significant Reactive Hypereosinophilia (HE): A Case Report

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome is a severe cutaneous drug reaction characterized by a skin rash, eosinophilia, atypical lymphocytosis, and involvement of multiple organs. The mortality rate of DRESS syndrome is moderate, and prompt diagnosis and treatment are essential. When DRESS syndrome is presented with significant hypereosinophilia (HE), it should be differentiated from other conditions that can cause HE through a comprehensive approach to diagnostic evaluation. Amoxicillin has been well-documented as a potential cause of DRESS syndrome. It is important to note that amoxicillin can trigger DRESS syndrome in patients who already have a known allergy to sulfasalazine, as well as when it is administered with a beta-lactamase inhibitor such as clavulanic acid. Here, we describe a case of amoxicillin alone-induced DRESS syndrome associated with significant reactive HE. A 39-year-old female presented with three days of shortness of breath, fatigue, facial swelling, and a generalized maculopapular skin rash. The patient endorsed taking amoxicillin two to three weeks prior to the presentation. Diagnostic tests revealed HE, significant generalized lymphadenopathy on computed tomography (CT) scans of the neck and abdomen, and bilateral interstitial infiltration on a CT scan of the chest suggestive of eosinophilic infiltration. Based on the European Registry of Severe Cutaneous Adverse Reactions (RegiSCAR) scoring system, the case was categorized as "probable" DRESS syndrome related to amoxicillin. High-dose steroids were initiated as the treatment of choice for suspected DRESS syndrome. Other potential causes of HE were investigated and ruled out. The patient showed significant clinical improvement, with the normalization of absolute eosinophil count (AEC) and complete resolution of lung infiltrates on a repeat CT scan of the chest. The case highlights the importance of conducting a comprehensive diagnostic evaluation to differentiate DRESS syndrome from other causes of HE when significant HE is present. Prompt treatment with high-dose steroids is essential in managing patients with severe symptoms associated with DRESS syndrome. It is crucial to consider amoxicillin as a potential trigger for DRESS syndrome, even when there is no history of sulfasalazine allergy or concurrent administration of a beta-lactamase inhibitor.