Langerin, also known as CD207, is a type II transmembrane receptor expressed on Langerhans cells. Langerhans cells are immature dendritic cells localized in the epidermis and mucosal epithelia that initiate innate and adaptive immune responses to skin-relevant antigens.

Tumors derived from Langerhans cells are classified into Langerhans cell histiocytosis (LCH) and Langerhans cell sarcoma (LCS). LCS is a rare dendritic cell tumor defined as a malignant high-grade variant of LCH. Differentiation between LCH, LCS and other tumors is difficult. The presence of Birbeck granules, CD1a and Langerin protein expression provides utility in differentiating Langerhans cell disorders from other non-Langerhans cell proliferations.