Dacomitinib-Induced Paronychia Associated With PRIDE Syndrome in a Patient With Non-Small Cell Lung Cancer.

Epidermal growth factor receptor (EGFR) inhibitors are essential for treating non-small cell lung cancer (NSCLC) with EGFR mutations, but they frequently cause cutaneous toxicities collectively referred to as papulopustules and/or paronychia, regulatory abnormalities of hair growth, itching, and dryness due to epidermal growth factor receptor inhibitors (PRIDE) syndrome. This case describes a 55-year-old male with advanced NSCLC who developed toe-predominant paronychia, a papulopustular rash localized to the trunk and limbs, and diarrhea four to eight weeks after initiating first-line therapy with dacomitinib. Notably, causality was evaluated using multiple validated tools - Naranjo, WHO-UMC, and Liverpool Causality Assessment Tool - all of which indicated a "probable" relationship. Importantly, these adverse effects were managed symptomatically without the need for discontinuation or dose reduction of dacomitinib. This case contributes to the literature by documenting an atypical anatomical distribution (toe-predominant), early onset, and successful continuation of therapy, highlighting the importance of early recognition, pharmacologic assessment, and adverse event reporting to optimize the safety of EGFR inhibitors in clinical practice.