Vemurafenib-induced eccrine squamous syringometaplasia

We report herein a patient treated with vemurafenib for a stage IV melanoma who developed an eruption related to eccrine squamous syringometaplasia (ESS). This entity is a well-described side effect of cytostatic therapies used for malignant neoplasia and is clinically characterized by a symmetric cutaneous eruption composed of papules and vesicles preferentially located on fold and intertriginous areas. It is histologically defined by a squamous metaplasia of eccrine ductal epithelium. ESS represents another skin eruption to be added to the list of cutaneous adverse events associated with vemurafenib, a selective BRAF inhibitor used to treat patients with metastatic melanoma harboring the V600E mutation. The discussion focuses on the pathogenesis of ESS secondary to vemurafenib and on alternative diagnoses.