Department of Anatomical Pathology, PathWest Laboratory Medicine, QEII Medical Centre, Nedlands, WA, Australia.
School of Medical and Health Sciences, Edith Cowan University, Perth, WA, Australia.
Cytopathology. 2022 Jan;33(1):84-92. doi: 10.1111/cyt.13015. Epub 2021 Jun 15.
To assess the utility of BRCA1-associated protein 1 (BAP1) immunohistochemistry (IHC) for the diagnosis of malignant pleural mesothelioma (MPM) in fluid samples with atypical cytology.
Pleural fluid samples with an atypical mesothelial proliferation (diagnostic categories: 'atypical' and 'suspicious') received between January 2015 and March 2018 at a tertiary referral centre were identified. Results of routine IHC testing were recorded for each case. BAP1 by IHC was performed and a final diagnosis sought from subsequent pathology specimens, medical records, or consensus clinical diagnosis.
Of 50 cases identified, 41 were reported as atypical and 9 as suspicious. Seven (14%) demonstrated loss of BAP1 staining, 40 retained BAP1 staining, 1 had heterogeneous staining, and 2 had insufficient cells for analysis. All seven cases with BAP1 loss were diagnosed with MPM on follow-up. Of those with retained BAP1, 52.5% (21) were subsequently diagnosed with MPM, while 40% (16) had non-MPM diagnoses after a median follow-up of 24 months. Three cases were not further investigated based on patient and clinician decision. The case with heterogeneous staining was diagnosed as mesothelioma by clinical consensus.
BAP1 IHC loss is highly specific for malignancy and has value as a rule-in test. Even in a tertiary centre with clinical interest in the cytological diagnosis of MPM this investigation was able to increase diagnostic accuracy beyond routine IHC studies. Cytological criteria remain valuable, as retained BAP1 in an atypical or suspicious mesothelial proliferation cannot exclude malignancy.
评估 BRCA1 相关蛋白 1（BAP1）免疫组织化学（IHC）在细胞学表现不典型的胸腔积液样本中用于诊断恶性胸膜间皮瘤（MPM）的效用。
在 2015 年 1 月至 2018 年 3 月期间，在一家三级转诊中心，我们确定了存在不典型间皮细胞增生（诊断类别：“不典型”和“可疑”）的胸腔积液样本。记录了每个病例的常规 IHC 检测结果。对这些胸腔积液样本进行了 BAP1 的 IHC 检测，并根据后续的病理标本、病历或共识临床诊断寻求最终诊断。
在确定的 50 个病例中，有 41 个被报告为不典型，9 个为可疑。7 例（14%）显示 BAP1 染色缺失，40 例保留 BAP1 染色，1 例存在异质性染色，2 例细胞数量不足无法进行分析。所有 7 例 BAP1 缺失的病例在随访中均被诊断为 MPM。在保留 BAP1 的病例中，52.5%（21 例）随后被诊断为 MPM，而 40%（16 例）在中位随访 24 个月后被诊断为非 MPM。基于患者和临床医生的决定，有 3 例未进一步进行调查。异质性染色的病例经临床共识诊断为间皮瘤。
BAP1 IHC 缺失高度提示恶性肿瘤，可作为规则内检测。即使在一个对 MPM 细胞学诊断有临床兴趣的三级中心，该检测也能够提高诊断准确性，超越常规 IHC 研究。细胞学标准仍然具有价值，因为在不典型或可疑的间皮细胞增生中保留的 BAP1 不能排除恶性肿瘤。
