Refractory multisystem Langerhans cell histiocytosis in an infant: use of vemurafenib as a therapeutic option.

Langerhans cell histiocytosis (LCH) is a rare disease that predominantly affects children, characterized by the abnormal clonal proliferation of Langerhans cells with a broad clinical spectrum and prognosis. Refractory LCH to standard treatment usually presents multisystem and risk organs involvement, and mainly affects children under 2 years of age. In these cases, more than half present the BRAF-V600E mutation; detection of this mutation is essential for targeted treatment, such as vemurafenib, a BRAF inhibitor. We present the case of a 6-month-old patient diagnosed with multisystemic LCH without involvement of risk organs, who responded poorly to first- and second-line therapy. A molecular biology study was performed, which reported a BRAF-V600E mutation. Treatment with vemurafenib was indicated, and a good clinical response was obtained after 2 weeks.