A Case of Purpuric Papulopustular Eruption on the Extremities Developed During Erlotinib and Ramucirumab Combination Treatment, Resulting in Complete Regression Without Oral Prednisone or Discontinuing Chemotherapy.

A 53-year-old woman undergoing combination therapy with epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor (VEGFR) inhibitors for advanced lung cancer with brain metastases developed pustules and punctate purpura on both lower extremities. Histopathological examination revealed neutrophilic infiltration around the hair follicles and erythrocyte extravasation in the perivascular regions near the hair roots, leading to a diagnosis of purpuric papulopustular eruptions. The rash improved with oral doxycycline (100 mg/day) and topical corticosteroids. This case demonstrates that extensive purpuric drug eruptions without symptoms of vasculitis can be effectively managed with oral antibiotics, without the need for chemotherapy discontinuation or systemic corticosteroids. EGFR inhibitors can induce purpuric papulopustular eruptions through follicular occlusion and damage to vascular endothelial cells via inflammatory cells. In our case, the treatment duration was longer than previously reported, suggesting that VEGFR inhibitors delay wound healing and endothelial cell repair, potentially contributing to the development of purpuric papulopustular eruptions. As combination therapy with EGFR and VEGFR inhibitors was only introduced in 2022, to the best of our knowledge, the present case is the first of purpuric papulopustular eruptions occurring during this treatment regimen.