Supplementary Material for: DNA Ploidy Analysis and Cell Block Immunohistochemistry in the Diagnosis of Malignant Effusions

Background: Effusion cytology is a major diagnostic tool in medicine and has both therapeutic and prognostic implications. One of the dilemmas encountered is the differentiation between atypical cells and reactive mesothelial cells. The use of ancillary tools can reduce this grey zone and help to achieve a definitive diagnosis. Objectives: The main objective of this study was to evaluate the role of flow cytometry (FCM) and cell block with immunohistochemistry (IHC), along with the clinicoradiological investigations, to achieve a final diagnosis in effusion cytology to the maximum extent possible. Method: A prospective study was conducted. Effusion fluids, showing adequate amount and cellularity, were processed for conventional cytology, ploidy analysis by FCM, and cell block analysis, followed by IHC wherever required. Conventional cytological analysis was done by 2 independent pathologists, to look for interobserver variation, if any. The final result was achieved on the basis of integration of the results of the aforementioned studies, cytological details, clinicoradiological information, tissue biopsy findings, and follow-up. Result: A total of 90 samples were analyzed. On cytological examination, observer I categorized 60% samples as benign and 18.8% (n = 17) as malignant versus 58% categorized as benign and 23.3% (n = 21) as malignant by observer II. Observer I reported 19 (21.1%) equivocal cases and observer II reported 16 (17.7%). When both pathologists were considered together, the number of equivocal cases increased to 20. Sensitivity and specificity of FCM were 96.67 and 100%, respectively, and 100% for the cell block. On combining all techniques, the equivocal cases were resolved and a total of 33 cases were reported as malignant. However, 3 cases could still not be categorized and were labeled inconclusive. Conclusion: Conventional cytology combined with cell block IHC and FCM has the potential to minimize the requirement of tissue biopsy for confirmation. If the first sample is used judiciously for all the techniques, this may reduce the requirement for a second sample and possibly also the time required for a definite diagnosis and the initiation of therapy.

背景：渗出液细胞学（effusion cytology）是医学领域的重要诊断工具，兼具治疗与预后指导价值。临床实践中面临的一大困境是非典型细胞与反应性间皮细胞的鉴别诊断，借助辅助检测工具可缩小这一诊断灰色地带，助力实现明确诊断。
研究目的：本研究的核心目标是评估流式细胞术（flow cytometry, FCM）、结合免疫组织化学（immunohistochemistry, IHC）的细胞块检测，联合临床放射学检查在渗出液细胞学诊断中最大限度实现最终确诊的作用。
研究方法：本研究为前瞻性研究。纳入标本量与细胞丰度均符合要求的渗出液样本，分别行常规细胞学检查、流式细胞术倍体分析、细胞块检测，必要时追加免疫组化检测。由2名独立病理医师开展常规细胞学分析，以评估观察者间差异（若存在）。最终诊断结果综合前述各项检测结果、细胞学特征、临床放射学资料、组织活检结果及随访信息综合得出。
研究结果：共纳入90例样本进行分析。细胞学检查中，观察者1将60%的样本判定为良性，18.8%（n=17）判定为恶性；观察者2则将58%的样本判定为良性，23.3%（n=21）判定为恶性。观察者1报告19例（21.1%）为不确定病例，观察者2报告16例（17.7%）。合并两名病理医师的判定结果后，不确定病例数增至20例。流式细胞术的敏感度与特异度分别为96.67%与100%，细胞块检测的敏感度与特异度均为100%。联合所有检测技术后，所有不确定病例均得到明确分类，共33例被判定为恶性，但仍有3例无法归类，标注为无法确诊。
研究结论：常规细胞学联合细胞块免疫组化及流式细胞术，有望减少确诊所需的组织活检需求。若能合理利用首份样本完成全部检测项目，则可降低二次采样的需求，同时可能缩短明确诊断及启动治疗所需的时长。