Langerhans cell histiocytosis (LCH) is a rare proliferative disease with a wide spectrum of clinical presentations and, as a consequence, the treatment choice is unclear. Recently, detection of the BRAF V600E mutation changed the perspective of this disease, suggesting a possible use for BRAF inhibitors in its treatment. Herein, a case is presented of a patient with LCH undergoing treatment with vemurafenib after several lines of therapy. After 4 months of vemurafenib treatment, skin lesions associated with cranial involvement were reduced in size at physical evaluation and nuclear imaging assessment showed a very good partial response, with the resolution of multiple lesions. Based on this very good partial response and because the patient tolerated treatment well, the patient was able to continue treatment with vemurafenib until disease progression nearly 10 months later. This approach should be considered for patients with severe and multiresistant LCH with a BRAF mutation. However, more studies are needed to evaluate the efficacy and duration of response in a larger patient population.

Langerhans cell histiocytosis (LCH) is a rare proliferative disease characterized by the presence of large and mononuclear cells that are normally involved in the antigen-presenting function. These cells are defined by the positivity of CD1a, CD68, S100, and CD207 at immunohistochemistry. 1 In lesions, LCH cells are included in a particular microenvironment, which is made of T cells, macrophages, and eosinophils that support disease progression through a local production of cytokines. 2 The prevalence of LCH is higher in childhood but not exclusive to this period. 3 In adults, the diagnosis is made typically between the 5th and 7th decades of life, with both sexes being equally affected. 4