532‐nm KTP Laser Treatment of Epidermal Growth Factor Receptor Inhibitor–Associated Paronychia: A Case Report

OBJECTIVES: Paronychia is a common and often painful cutaneous adverse event of epidermal growth factor receptor inhibitor therapy that can impair function and quality of life. We report the first known case of amivantamab-associated paronychia successfully treated with 532-nm potassium-titanyl-phosphate laser. MATERIALS AND METHODS: A 67-year-old man with metastatic non-small cell lung cancer receiving amivantamab developed painful periungual inflammation with pyogenic granuloma-like changes involving multiple fingers and both great toes after failing multiple topical therapies. A representative lesion on the left fourth digit was selected for treatment and underwent two sessions of 532-nm KTP laser therapy. Treated and untreated digits were compared for clinical response. RESULTS: Following two treatment sessions, the treated digit demonstrated marked improvement in erythema, pain, and friability. Untreated digits remained inflamed and symptomatic, serving as a within-patient comparator. No adverse events were observed. CONCLUSION: Given its superficial vascular targeting mechanism and broad clinical availability, the 532-nm KTP laser may represent a practical and effective therapeutic option for refractory EGFRI-associated paronychia. To our knowledge, this is the first reported case of successful treatment of amivantamab-associated paronychia with a 532-nm KTP laser.