{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T10:11:12Z","timestamp":1788948672738,"version":"build-2803163510"},"reference-count":25,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Clin. Med.","JCM"],"abstract":"<jats:p>Background: Tuberculous pleural effusion (TPE) occasionally presents with polymorphonuclear leukocyte (PMN)-predominant pleural fluid (PF) and elevated serum C-reactive protein (CRP), mimicking parapneumonic effusion (PPE). We investigated factors distinguishing TPE from PPE in this diagnostically challenging setting. Methods: We retrospectively reviewed consecutive patients with confirmed TPE or PPE at a tertiary referral center (2010\u20132024). Patients with serum CRP \u2265 10 mg\/dL were classified according to PF PMN-predominance. Independent discriminators between PMN-predominant TPE and PPE were identified using multivariable Firth logistic regression. Results: Among 414 patients with confirmed TPE, 108 (26%) had serum CRP \u2265 10 mg\/dL, including 20 with PMN-predominance and 88 without. Anti-tuberculosis treatment was modestly delayed in the PMN-predominant group (p = 0.017). These 20 patients were compared with 335 PPE patients showing the same CRP\/PMN profile. Pulmonary nodular lesions on chest computed tomography and PF adenosine deaminase (ADA) were independent discriminators. A composite two-tier rule\u2014nodular lesions present or PF ADA &gt; 80 IU\/L if absent\u2014achieved an AUROC of 0.925, 80.0% sensitivity, and 86.2% specificity. Conclusions: In patients with PMN-predominant pleural effusion and elevated serum CRP, this simple, readily available rule may help identify patients warranting early pleural biopsy and heightened suspicion for TPE before microbiological confirmation.<\/jats:p>","DOI":"10.3390\/jcm15186976","type":"journal-article","created":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T09:24:02Z","timestamp":1788945842000},"page":"6976","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Distinguishing Polymorphonuclear Leukocyte-Predominant Tuberculous Pleural Effusion from Parapneumonic Effusion in Patients with Elevated Serum C-Reactive Protein"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-6690-2779","authenticated-orcid":false,"given":"Seongwon","family":"Shin","sequence":"first","affiliation":[{"name":"Department of Pulmonology, Kyungpook National University Hospital, Daegu 41944, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8958-0886","authenticated-orcid":false,"given":"Chi Young","family":"Jung","sequence":"additional","affiliation":[{"name":"Department of Pulmonology, Daegu Catholic University Medical Center, Daegu 42472, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"given":"Chang Ho","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8111-7320","authenticated-orcid":false,"given":"Jaehee","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1056\/NEJM199902113400607","article-title":"Acute-phase proteins and other systemic responses to inflammation","volume":"340","author":"Gabay","year":"1999","journal-title":"N. 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