Erdheim-Chester Disease and Other Histiocytoses

Erdheim-Chester disease (ECD) was first described as “lipoid granulomatose” by Jakob Erdheim and William Chester in 1930 [1]. This non-Langerhans histiocytosis of unknown origin is rare, with less than 1000 cases as of December 2015 [2–5]. ECD, morphologically and immunohistochemically, appears to be a member of the juvenile xanthogranuloma (JXG) family that involves the long bones in a bilateral fashion. ECD can be distinguished from Langerhans cell histiocytosis (LCH) by the characteristic xanthogranuloma immunostaining, which is factor XIIIa + /CD68 + /CD163 + /fascin + and S100 − /CD1a − /Langerin − /Birbeck granules − [6].