[A rare disease; Erdheim-Chester disease presenting with spontaneous pneumothorax].

Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytosis of unknown etiology, it is characterized by organ infiltration of foamy histiocytes. Diagnosis of ECD involves the analysis of histiocytes in tissue biopsies: these are typically CD68+ CD1a-. These characteristic histiocytes may be found in almost any tissue in cases of ECD. We present an interesting case of ECD that was presented by spontaneous pneumothorax and neurological involvement.