ObjectiveTo explore the clinical manifestations, pathological features, differential diagnosis and gene mutation status in patients with pulmonary involvement of Erdheim-Chester disease (ECD).

MethodsThe clinical data of 4 cases of Erdheim-Chester disease admitted to Peking Union Medical College Hospital from October 2014 to August 2016 were examined for imaging, microscopic and immunohistochemitry findings, and BRAFV600E mutation. The related literatures were reviewed.

ResultsAmong the 4 cases, there were 3 males and 1 female, aging from 7 to 47 years, and the average age was 34.5 years. They complained of chest tightness, shortness of breath and bone pain. They all had multiple bone lesions, involving the long bones, skulls and vertebrae, and imaging showed increased bone uptake and bone sclerosis. CT scan showed pleural thickening or pleural effusion(4/4), widened lobular septa(3/4), bronchial vascular bundle thickening(3/4), multiple patchy ground glass and solid shadows(4/4), and cystic shadows(1/4). Multiple bone lesions were the main extrapulmonary manifestations. All the cases had multiple bone lesions, involving the long bones, skulls and vertebrae, and showed increased bone uptake and bone sclerosis. Surgical biopsy of the thoracic tissue was performed in all 4 cases (pleural in 1 case, lung in 2, anterior mediastinal mass in 1). Microscopically, the lesion was composed of spindle-shaped fibroblasts and foamy histiocytes enmeshed in reactive fibrous tissue. Lymphocytes and plasma cells were also found. Immunohistochemically, all the histiocytes were positive for CD ₆₈, and none of them expressed CD1a. All cases were detected by real-time quantitative PCR for BRAFV600E gene mutation.

ConclusionsThe pulmonary involvement of Erdheim-Chester disease is rare, with clinical manifestations of chest tightness, shortness of breath, and some have no obvious respiratory symptoms. Pulmonary involvement in Erdheim-Chester disease has important manifestations, in which foam-like tissue cells with diffuse distribution along the lymphatic enmeshed in reactive fibrous tissue. It should be differentiated from diffuse interstitial lung diseases and metastatic tumors. The clinical features are often manifested as pleural thickening and pleural effusion, with multiple bone sclerosis lesions.BRAFV600E mutation detection is helpful for the diagnosis.