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

objectivesParonychia 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

methodsA 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.

resultsFollowing 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.

conclusionGiven 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.