Langerhans Cell Histiocytosis: Evidence Leans Toward a Neoplastic Origin

Langerhans cell histiocytosis (LCH) is a heterogeneous disease whose course may vary from spontaneous resolution to fatal progression. An older designation, histiocytosis X, reflected its unknown etiology; the current name recognizes morphological and immunohistochemical resemblances to cutaneous Langerhans cells (LC). Presence of the antibodies CD1a, S-100, and CD207 (Langerin) currently identify LCH. Prompted by recent findings of BRAFV600E mutations in LCH, these researchers used immunohistochemical VE1 antibody staining and PCR amplification in 89 patients with LCH.

VE1 staining detected a mutant protein in 38% of cases. BRAFV600E mutations were found in 39% of 46 evaluable lesions; the sole instance of a V600K mutation was negative for …