Presence of Erdheim-Chester disease and Langerhans cell histiocytosis in the same patient: a report of 2 cases.

The histiocytic disorders Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD), can both present with multisystem involvement, with the central nervous system and the bone, skin, neuroendocrine, cardiac, respiratory, and gastrointestinal systems potentially affected. The 2 entities occasionally can be difficult to distinguish. Both rarely affect the orbit and the central nervous system, and although there are rare reports of patients with coexistent LCH and ECD, there are no reported cases of the 2 diseases that involve both the orbital and neuroendocrine systems. We report 2 such cases, and review the literature of cases of LCH and ECD occurring in the same patient. The presentation of LCH and ECD in certain patients suggests a possible abnormality in the common CD34 progenitor cell. The coexistence of the 2 disease states should be suspected in patients with atypical presentations of either disorder.