Association between clinicopathologic characteristics and BRAF expression in Chinese patients with Langerhans cell histiocytosis.

Background: The identification of V-raf murine sarcoma viral oncogene homolog B1 (BRAF) mutations has been recommended in patients with Langerhans cell histiocytosis (LCH) with difficult diagnosis and failure of first-line treatment. The reported frequencies of BRAF mutations vary in Chinese patients with LCH.

Methods: We conducted a retrospective analysis of LCH patients with a definitive pathological diagnosis who were hospitalized between 2013 and 2017. The BRAF mutations were detected with the human BRAF amplification refractory mutation system-PCR (ARMS-PCR) kit from the collected tissue samples.

Results: This study consisted of 46 male (68.7%) and 21 female (31.3%) patients, with a mean age of 29.1 years (range, 2-76 years). Most were adults (45/67.2%) with the multisysytem-LCH (MS-LCH) disease subtype (49/61.3%). The overall frequency of BRAF mutations was 22.4% (15 of 67 patients), confirmed by PCR analysis. These mutations were not closely correlated with age (nonadults vs. adults = 5/22.7% vs. 10/22.2%, P = 0.54), gender (female vs. male = 9/19.6% vs. 6/28.6%, P = 0.61), LCH classification type (single system: MS-risk organ : MS-risk organ = 3/16.7%: 12:28.6%: 0, P = 0.19) or prognosis (cured: improved/stable: exacerbated: died = 4/44.4%: 19.2%: 20%: 0, P = 0.37). There were 33 patients (49.2%) with lung involvement, and 12 patients (36.3%) underwent lung biopsies; after screening, four patients were diagnosed with solitary pulmonary LCH, all of whom were negative for BRAF mutations.

Conclusion: The BRAF mutation rate in patients with LCH was lower than those reported in other studies. In addition, BRAF mutations might not be correlated with age, gender, LCH classification type or prognosis for Chinese cases.