JPSIM Journal of Pakistan Society of Internal Medicine J Pak Soc Intern Med 2709-8729 2710-0804 Pakistan Society of Internal Medicine 10.70302/jpsim.v7i2.2628 jpsim.v7i2.2628 Original Research Diagnostic Accuracy of Pleural Fluid Protein in Differentiating Tuberculous and Malignant Pleural Effusion Rehman Karishma karishmarehman46661@import.invalid * Younas Mohammad Farooqi Rukhsana Javed Saeed Rabia Sajjad Sheema Ashraf Saadia MTI Khyber Teaching Hospital Peshawar *Correspondence: Karishma Rehman (karishmarehman46661@import.invalid) 03 06 2026 2026 7 2 141 145 16 12 2025 13 04 2026 04 05 2026 Copyright © 2026 The Author(s) 2026 The Author(s) https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective

The utility of pleural fluid protein in differentiating between malignant and tuberculous conditions in patients with pleural effusions, with histology serving as the gold standard for diagnosis.

 Methodology

Cross-sectional (validation) study. Patients were referred from in- and out-of-door patient departments. Patients fulfilling the inclusion criteria underwent Abrams needle biopsies according to routine and following the obtaining of informed written consent, and the pleural tissue was examined by a single histopathologist. A pleural fluid protein cut-off value of 5 g/dl for tuberculosis was marked.

 Results

In this study, we identified 209 patients with suspected tuberculous or malignant pleural effusions. Mean age was 42.7 + 10.8 SD. In the diagnosis of cancer, pleural fluid protein has a positive predictive value of 35.9%, a negative predictive value of 98.82%, and sensitivity and specificity of 87.5% and 87.05%, respectively. The overall diagnostic performance of pleural fluid protein for cancer was 87.08%.

 Conclusion

When combined with a suitable clinical setting, the pleural fluid total protein level is a useful diagnostic tool for suspected tuberculous or malignant pleural effusions.

 Keywords tuberculous pleural effusion malignant pleural effusion exudates pleural biopsy pleural fluid protein. Ethics Statement

Ethics committee: Ethics Committee, Khyber Medical College, Peshawar, Pakistan. Approval number: 224/DME/KMC, dated April 13, 2023.

 References Koegelenberg CFN, Shaw JA, Irusen EM, Lee YCG. Contemporary best practice in the management of malignant pleural effusion. Ther Adv Respir Dis. 2018;12:1753466618785098 Ping Luo, Kaimin Mao, Juanjuan Xu, Feng Wu, Xuan Wang, Sufei Wang, et al. Metabolic characteristics of large and small extracellular vesicles from pleural effusion reveal biomarker candidates for the diagnosis of tuberculosis and malignancy. J Extracellular Vesicles. 2020; 10.1080/20013078.2020.1790158 Kaul V, McCracken DJ, Rahman NM, Epelbaum O. Contemporary Approach to the Diagnosis of Malignant Pleural Effusion. Ann Am Thorac Soc. 2019;16(9):1099-106 Zhang X, Duan H, Yu Y, Ma C, Ren Z, Lei Y, et al Zhang M. Differential diagnosis between benign and malignant pleural effusion with dual-energy spectral CT. PLoS One. 2018;13(4):e0193714 Kim CH, Oh HG, Lee SY, Lim JK, Lee YH, Seo H, et al. Differential diagnosis between lymphoma-associated malignant pleural effusion and tuberculous pleural effusion. Ann Transl Med. 2019 Aug;7(16):373 10.21037/atm.2019.07.17 Petborom P, Dechates B, Muangnoi P. Differentiating tuberculous pleuritis from other exudative lymphocytic pleural effusions. Ann Palliat Med 2020;9(5):2508-15. Yang MF, Tong ZH, Wang Z, Zhang YY, Xu LL, Wang XJ, et al, Jiang T, Shi HZ. Development and validation of the PET-CT score for diagnosis of malignant pleural effusion. Eur J Nucl Med Mol Imaging. 2019;46(7):1457-67 Mercer RM, Corcoran JP, Porcel JM, Rahman NM, Psallidas I. Interpreting pleural fluid results . Clin Med (Lond). 2019;19(3):213-7 Takeuchi E, Okano Y, Machida H, Atagi K, Kondou Y, Kadota N, et al. Eosinophilic pleural effusion due to lung cancer has a better prognosis than non-eosinophilic malignant pleural effusion. Cancer Immunol Immunother. 2022;71(2):365-72 Schwalk AJ, Ost DE, Saltijeral SN, De La Garza H, Casal RF, Jimenez CA, et al. Risk Factors for and Time to Recurrence of Symptomatic Malignant Pleural Effusion in Patients With Metastatic Non-Small Cell Lung Cancer with EGFR or ALK Mutations. Chest. 2021;159(3):1256-64 Farraga M, El-Masrya A, Shoukria AM, ElSayedb M. Prevalence, causes, and clinical implications of pleural effusion in pulmonary ICU and correlation with patient outcomes. Egypt J Bronchol. 2018;12(2):247–52. Ferrer J. Tuberculous pleural effusion and tuberculous empyema. Crit Care Med 2001;22(6):637-46. Porcel JM, Vives M. Differentiating tuberculous from malignant pleural effusion: A scoring model. Med Sci Monit 2003;9(2):175-80. Chierakul N, Kanitsap A, Chaiprasert A, Virivataveekul R. A simple C- C-reactive protein measurement for the differentiation between tuberculous and malignant pleural effusion. Respirol. 2004;9(1):66-9. Antonangelo L, Vargas FS, Seiscento M, Bombarda S, Teixera L, Sales RK. Clinical and laboratory parameters in the differential diagnosis of pleural effusion secondary to tuberculosis or cancer. Clin 2007;62:585-90. Javaid A, Amjad M, Shah N, Samad A, Ullah Z. Diagnostic evaluation of exudative pleural effusion, the value of pleural biopsy. Pak J Chest Med 2001;7(1):12-20. Khaliq MR. Pleural biopsy by Abrams punch needle pattern and frequency of histopathological lesions encountered in patients with exudative pleural effusion. Ann Abbasi Shaheed Hosp Karachi Med Dent Coll 2003;8(1):6-11. Parkin DM, Bray F, Ferlay J, Pisani P. Global cancer statistics, 2002. Cancer J Clin 2005;55(1):4-108. Fishman AP. Disorders of the pleural space. In: Elias JA, Fishman JA, Grippi MA, Kaiser LR, Senior RM, (edi). Fishman’s pulmonary diseases and disorders. 3rd ed. Washington, DC: McGraw-Hill; 1997:p.1389-452. Heidari B, Bijani K, Eissazadeh M, Heidari P. Exudative pleural effusion: effectiveness of pleural fluid analysis and pleural biopsy. East Meditter Health J 2007;13(3):765-73. Haro M, Ruiz-Manzano J, Gallego M, Abad J, Manterola JM, Morera J. Pleural tuberculosis: analysis of 105 cases. Enferm Infecc Microbiol Clin 1996;14(2):285-9. Liam CK, Lim KH, Wong CM. Differences in pleural fluid characteristics, white cell count, and biochemistry of tuberculous and malignant pleural effusions. Med J Malaysia 2000;55(1):21-8. Melo AF, Santos ML. Diagnóstico da tuberculose pleural pela ada, isolada ou combinada a outras variáveis, inclusive em HIV positivos. Folha Med 2000;119(1):19-21.