Adult Onset of BRAFV600E-Mutated Langerhans Cell Histiocytosis with Cutaneous Involvement Successfully Diagnosed by Immunohistochemical Staining

Abstract

Langerhans cell histiocytosis (LCH) is characterized by the clonal proliferation of Langerhans cells; it is categorized as a single-system disease with single or multifocal lesions, and as a multi-system disease with or without the risk of organ involvement. Although the skin is not categorized as a risk organ, the precise diagnosis of skin lesions is necessary to determine the protocol for the treatment of LCH. In this report, we describe a 28-year-old Japanese man with adult onset of BRAF^V600E-mutated LCH with cutaneous involvement successfully diagnosed by immunohistochemical staining. Our report suggests that immunohistochemical staining for the BRAF^V600E gene could be a diagnostic tool to determine the clinical type of LCH.