An unusual case of interstitial lung disease in a patient with cardiopulmonary syndrome as the initial presentation of Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a very rare disorder with only approximately 600 cases reported in the literature. ECD has been recently reclassified as a histiocytic dendritic cell neoplasm. The clinical spectrum ranges from asymptomatic tissue accumulation of histiocytes to invasive tissue infiltration, which can cause fulminant multisystem failure. It typically presents with bone pain and constitutional symptoms. Extraosseous manifestations are not uncommon. ECD-associated interstitial lung disease has been described in 20%-35% of patients. Diagnosis is primarily by tissue biopsy and immunohistochemistry showing xanthogranulomas composed of foamy histiocytes that stain positive for CD68, CD14 and CD163 and negative for CD1á and langerin. We report a case of ECD in a young man with cardiopulmonary involvement who presented with haemoptysis and dyspnoea. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.