LCH lesion histology. Images demonstrate typical histology of LCH lesion obtained from a bone biopsy with pathologic histiocytes and inflammatory infiltrate. (A-B) Hematoxylin and eosin stain demonstrates histiocytes with pale cytoplasm and reniform nuclei. (C) Birbeck granules on electron microscopy; immunohistochemistry strongly positive for (D) langerin/CD207, (E) CD1a, and (F) S100a.  (Courtesy of M. J. Hicks)