Cutaneous Langerhans cell histiocytosis with gastrointestinal involvement treated with dabrafenib

LCH: Langerhans cell histiocytosis INTRODUCTION Langerhans cell histiocytosis (LCH) is a rare disorder characterized by an abnormal clonal proliferation of histiocytes, with adult-onset LCH accounting for an estimated 30% of cases. The clinical spectrum of LCH varies widely, from asymptomatic singleorgan involvement to severe and potentially fatal multisystem disease. Although cutaneous lesions are frequently encountered, gastrointestinal involvement in LCH is exceedingly rare, especially in the adult population. Effective treatment for LCH is poorly characterized because of rarity and heterogeneity of the disease. Twenty percent to 60% of LCH cases harbor the BRAF V600E proto-oncogene mutation, and reports show favorable response to BRAF inhibitors in this population. Dabrafenib is a targeted therapy that selectively inhibits the extracellular signalerelated kinase pathway in patients with BRAF V600E mutated malignancies. Here we describe a case of adult primary cutaneous LCH with late-onset gastrointestinal involvement responsive to dabrafenib.