Multiple palpebral syringomas occurring after initiation of BRAF inhibition therapy in a patient with metastatic melanoma

MAPK: mitogen-activated protein kinase MEK: MAPK/ERK kinase INTRODUCTION Several skin lesions resulting from keratinocyte hyperproliferation have been observed in melanoma patients receiving BRAF inhibitor monotherapy. The most common of these lesions are verrucal keratosis, Grover disease, plantar hyperkeratosis, actinic keratosis, cutaneous squamous cell carcinoma, and keratosis pilaris. More rare types of keratinocyte hyerproliferation occurring within the eccrine glands, as in eccrine syringometaplasia, have also been reported. Most of these side effects are thought to result from the paradoxical activation of the mitogen-activated protein kinase (MAPK) pathway. Here we present the case of a patient treated with BRAF inhibitors for metastatic melanoma who subsequently had multiple palpebral syringomas that lasted during the monotherapy periods and regressed after the addition of a MAPK/ERK kinase (MEK) inhibitor.