Toi Pampa Ch, Subramaniam Apoorvalakshmi, Joseph Noyal Mariya, Siddaraju Neelaiah
Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
J Cytol. 2025 Apr-Jun;42(2):82-87. doi: 10.4103/joc.joc_37_24. Epub 2025 May 29.
Detection of extrapulmonary tuberculosis (EPTB) by Ziehl-Neelsen (Z-N) staining in fine needle aspirates is challenging due to the low yield of acid-fast bacteria (AFB). Mycobacterial culture, the gold standard, takes 4-8 weeks. Polymerase chain reaction with 100% sensitivity and 92.1% specificity is expensive. Mycobacterial antigens produced by the tubercle bacilli consist of several proteins and enzymes. The protein purified from is called MPT. The MPT64, a 24-kd protein, has not been detected in non-tuberculous mycobacteria. We aim to study the role of immunocytochemical (ICC) in the detection of EPTB in fine needle aspiration cytology materials by using MPT64 antibody and compare it with culture and Z-N staining, as ICC is not routinely practiced for diagnosing EPTB.
A total of 134 patients having enlarged nodes with suspected EPTB were included; however, only 96/134 cases were suitable for statistical analysis. Papanicolaou, May-Grünwald-Giemsa, Z-N staining, ICC, and mycobacteria culture were performed.
AFB was positive in 16%, 22.9% of culture-positive, and 11% of MPT64 positive. The sensitivity and specificity of ICC compared to mycobacterial culture were 45.4% and 99%, respectively. ICC and culture had a moderate agreement with the Kappa value of 0.535. The positive and negative predictive values of ICC with culture were 91% and 86%, respectively.
This study tried to improve the technique's sensitivity to facilitate its use in routine laboratory practice. Nonetheless, our results showed no significant improvement over the currently popular Z-N stain, although a comparison between the ICC technique performed on smears and cell block sections showed better results in the latter.
由于抗酸杆菌（AFB）检出率低，在细针穿刺抽吸物中通过萋-尼（Z-N）染色检测肺外结核（EPTB）具有挑战性。作为金标准的分枝杆菌培养需要4至8周。灵敏度为100%、特异性为92.1%的聚合酶链反应成本高昂。结核杆菌产生的分枝杆菌抗原由几种蛋白质和酶组成。从[具体物质]中纯化的蛋白质称为MPT。MPT64是一种24kd的蛋白质，在非结核分枝杆菌中未被检测到。我们旨在研究免疫细胞化学（ICC）在细针穿刺细胞学材料中使用MPT64抗体检测EPTB的作用，并将其与培养和Z-N染色进行比较，因为ICC在诊断EPTB方面并非常规操作。
共纳入134例有肿大淋巴结且怀疑为EPTB的患者；然而，仅96/134例适合进行统计分析。进行了巴氏染色、迈-格-姬染色、Z-N染色、ICC和分枝杆菌培养。
AFB阳性率为16%，培养阳性率为22.9%，MPT64阳性率为11%。与分枝杆菌培养相比，ICC的灵敏度和特异性分别为45.4%和99%。ICC与培养的一致性中等，Kappa值为0.535。ICC对培养的阳性和阴性预测值分别为91%和86%。
本研究试图提高该技术的灵敏度以促进其在常规实验室实践中的应用。尽管如此，我们的结果显示与目前常用的Z-N染色相比没有显著改善，尽管在涂片和细胞块切片上进行的ICC技术比较显示后者结果更好。
