結核性肋膜積液之一病例報告與文獻回顧

A Case Report of Tuberculous Pleural Effusion and Literature Review

結核病為慢性傳染病，結核性肋膜積液為肺外結核中第2常見的表現，目前的標準診斷仍依賴結核菌培養，因培養耗時，長達數週且敏感度有限，使得診斷相當困難。本案例探討一位91歲男性病人，因發燒、咳嗽及右胸痛就醫，胸部影像發現右側肋膜積液與肺塌陷。2次肋膜積液檢測分析顯示為滲出性、以淋巴球為主之肋膜積液，ADA（Adenosine deaminase）值中等（18–29 U/L），3次痰液分枝桿菌耐酸性染色檢驗及分枝桿菌培養皆為陰性，2次肋膜積液分析顯示分枝桿菌耐酸性染色檢驗皆為陰性且結核分枝桿菌DNA檢查（PCR for Mycobacterium tuberculosis complex）亦沒有檢測到結核菌，後來肋膜積液培養出M. tuberculosis complex，故於住院後第17日開始抗結核藥物治療，之後病況逐漸改善。文獻指出肋膜積液ADA值與L/N（neutrophils/lymphocytes）比值有助診斷胸膜結核，但特異性有限，需結合培養或分子快速檢定，但敏感度不高；雖然進一步胸膜活檢有較高的敏感度和特異性，卻有其侵入性的風險，並非每位病人都適合。因此，對於原因未明之淋巴球為主的肋膜積液，應考慮結核性胸膜炎的可能性，並適當的應用目前的診斷工具來進行診斷或排除。

Tuberculosis is a chronic infectious disease. Tuberculous pleural effusion (TPE) is the second most common manifestation of extrapulmonary tuberculosis. However, the current standard diagnosis still relies on mycobacterial culture, which is challenging due to its prolonged turn-around time and limited sensitivity. This report presents a case of a 91-year-old male patient with fever, cough, and right-sided chest pain. Chest imaging revealed right-sided pleural effusion with lung collapse. Two thoracenteses revealed exudative, lymphocyte-predominant pleural effusions. The pleural fluid adenosine deaminase (ADA) levels were moderate (18–29 U/L). Acid-fast staining and mycobacterial cultures of sputum were negative. Acid-fast staining of the pleural fluid was also negative on two occasions, and polymerase chain reaction (PCR) testing for Mycobacterium tuberculosis complex DNA was negative as well. Eventually, M. tuberculosis complex was isolated from pleural fluid culture weeks later, and anti-tuberculosis therapy was initiated on hospital day 17, leading to clinical improvement. According to the literature review, mycobacterial culture is current gold standard of TPE and together with rapid molecular diagnostics of PCR are specific to the diagnosis but suffer from low sensitivity. By contrast, pleural ADA levels and the lymphocyte-to-neutrophil (L/N) ratio can aid in the diagnosis of TPE with high sensitivity although their specificity is limited. While pleural biopsy offers higher sensitivity and specificity, it is invasive and may not be suitable for all patients. Therefore, in cases of unexplained lymphocyte-predominant pleural effusion, TPE should be considered, and currently available diagnostic tools should be appropriately applied to establish or exclude the diagnosis.