Histopathologic Features of Erythematous Papulopustular Eruption to Epidermal Growth Factor Receptor Inhibitors in Cancer Patients

The study investigated the histopathologic features of erythematous papulopustular eruption (EPPE) in 39 cancer patients treated with epidermal growth factor receptor (EGFR) inhibitors, primarily cetuximab and erlotinib. It found that EPPE was characterized by neutrophilic subcorneal or intraepidermal pustules and a polymorphous infiltrate of the superficial dermis in the early stages, progressing to lymphocytic perifolliculitis and/or suppurative folliculitis later. Severe EPPEs were associated with widespread dermis inflammation, particularly in patients treated with cetuximab, while hair follicle inflammation was noted only in mild to moderate cases. The study highlighted the correlation between histopathologic signs, clinical severity, and the specific EGFR inhibitor used.