DERMATOGRAPHISM MAY BE AN UNRECOGNIZED FEATURE OF SERUM SICKNESS-LIKE REACTION

Introduction

Serum sickness-like reaction (SSLR) is a syndrome characterized by urticarial-like rash with arthralgia/arthritis. Oral drug challenge is recommended in patients with a history of SSLR to antibiotics. Some studies have reported immediate reactions upon challenge. Previous studies stated that the presence of dermatographism excludes the diagnosis of SSLR. Identifying dermatographism in SSLR patients at time of oral challenge is vital to avoid mislabeling dermatographic urticaria as an immediate drug reaction.

Methods

We reviewed patients with SSLR history who presented to clinic between February 2022 to January 2024. Data collected included age, sex, the antibiotic implicated, and the presence of dermatographism on physical exam.

Results

Of the 24 patients identified with a history of SSLR, 71% were male, with a median age of 2. The implicated antibiotics included amoxicillin (54%), amoxicillin-clavulanic acid (8%), and cefdinir (38%). 100% of patients tolerated graded oral challenge. On physical exam, 17 of the 24 patients with SSLR had dermatographism, accounting for 71% of the cases. The previously published rate of dermatographism in the general-pediatric population is reported to be 24%. Using a two-sided test of proportion, we found the rate of dermatographism in our cohort was significantly higher compared to the previously published rate in the general-pediatric population (p<0.001).

Conclusion

We identified that dermatographism at time of oral challenge is an exam feature associated with SSLR. If reproduced in future studies, this association may redefine SSLR criteria, suggest underlying pathophysiology, or serve as important information to avoid misclassifying minor cutaneous symptoms as drug allergy after oral challenge.