Pierry Clémence, Caumont Charline, Blanchard Elodie, Brochet Camille, Dournes Gael, Gros Audrey, Bandres Thomas, Verdon Séverine, Marty Marion, Bégueret Hugues, Merlio Jean-Philippe
Department of Pathology, CHU Bordeaux, Pessac, F-33604, Bordeaux, France.
Laboratory of Tumor Biology and Tumor Biobank, CHU Bordeaux, Pessac, F-33604, Bordeaux, France.
Virchows Arch. 2018 Feb;472(2):247-258. doi: 10.1007/s00428-017-2185-0. Epub 2017 Jul 15.
The neoplastic nature of pulmonary Langerhans cell histiocytosis (PLCH) is still debated. As the detection of BRAF and MAP2K1 mutations in patients with PCLH is now considered for such assessment, the aim of our study was to evaluate digital droplet polymerase chain reaction (ddPCR) in PCLH diagnosis. We retrospectively analyzed BRAF detection in a cohort of 42 PCLH tissues and 18 bronchoalveolar lavages (BALs) by ddPCR, immunohistochemistry, high-resolution melting PCR (HRM), and next-generation sequencing (NGS). The presence of BRAF mutation was assessed by at least two concordant techniques to further evaluate specificity and sensitivity of each method. The BRAF mutation prevalence was detected in 18 out of 41 cases by ddPCR, 10 out of 36 cases by HRM PCR, and 16 out of 31 cases by NGS. BRAF immunohistochemistry sensitivity was 94%, and specificity was 79%. HRM PCR sensitivity was only 59%, and specificity was 100%. NGS sensitivity and specificity were 100% for interpretable cases (n = 31), but in 11 cases, this technique was non-contributive. The analysis of BAL samples by ddPCR revealed a BRAF mutation both in tissue and in BAL samples in one patient, a wild-type status both in tissue and in BAL samples in two patients, and a wild-type BRAF status in BAL and a BRAF mutation in tissue samples in four patients. The study supports the usefulness of ddPCR for BRAF status assessment in either tissue or BAL samples to increase the accuracy of PLCH diagnosis.
肺朗格汉斯细胞组织细胞增多症（PLCH）的肿瘤性质仍存在争议。鉴于目前考虑通过检测PCLH患者的BRAF和MAP2K1突变进行此类评估，我们研究的目的是评估数字液滴聚合酶链反应（ddPCR）在PCLH诊断中的作用。我们通过ddPCR、免疫组织化学、高分辨率熔解PCR（HRM）和下一代测序（NGS），对42例PCLH组织和18例支气管肺泡灌洗（BAL）样本进行回顾性BRAF检测分析。通过至少两种一致的技术评估BRAF突变的存在，以进一步评估每种方法的特异性和敏感性。通过ddPCR在41例中的18例检测到BRAF突变，通过HRM PCR在36例中的10例检测到，通过NGS在31例中的16例检测到。BRAF免疫组织化学敏感性为94%，特异性为79%。HRM PCR敏感性仅为59%，特异性为100%。对于可解释的病例（n = 31），NGS敏感性和特异性均为100%，但在11例中，该技术无诊断价值。通过ddPCR对BAL样本进行分析，发现1例患者的组织和BAL样本中均存在BRAF突变，2例患者的组织和BAL样本均为野生型，4例患者的BAL样本为BRAF野生型而组织样本存在BRAF突变。该研究支持ddPCR在评估组织或BAL样本中BRAF状态以提高PLCH诊断准确性方面的作用。
