Evaluation of clinicopathologic characteristics and the BRAF V600E mutation in Erdheim-Chester disease among Chinese adults.

Erdheim-Chester disease (ECD) is a rare form of histiocytosis with a broad, non-specific clinical spectrum. Here, we retrospectively evaluated the clinical and pathologic characteristics, presence of the BRAF V600E mutation, treatment options, and outcomes of Chinese patients diagnosed with ECD at our center. Patients diagnosed with ECD between January 2010 and April 2015 at Peking Union Medical College Hospital were included for study. We evaluated baseline characteristics, reviewed histological material, and tested for the presence of the BRAF V600E mutation using immunohistochemistry and polymerase chain reaction (PCR). Sixteen patients were diagnosed with ECD. Median disease duration (from the first symptom to diagnosis) was 22.5 months (range, 3-100 months). The main sites of involvement included bone (93.8 %), cardiovascular region (43.8 %), skin (31.3 %), central nervous system (25 %), and "hairy kidney" (25 %). The BRAF V600E mutation was detected in 68.8 % patients using PCR and 50 % patients with immunohistochemistry. Three patients could not be diagnosed using histological analysis owing to similarities with Rosai-Dorfman disease, and diagnosis in these cases was confirmed based on the BRAF V600E mutation status. Ten patients (62.5 %) received IFN-α as first-line treatment. Thirteen patients (81.3 %) were still alive at median follow-up of 14.5 months. ECD remains a largely overlooked disease, and increased recognition by clinicians and pathologists is necessary for effective diagnosis and treatment. The presence of the BRAF V600E mutation may facilitate discrimination of ECD from other non-Langerhans cell histiocytoses.