A 26-year-old man presents with 3 weeks of low-grade fever, right-sided pleuritic pain and breathlessness. Chest radiograph shows a moderate right pleural effusion. Fluid analysis: protein 4.6 g/dL, LDH 420 IU/L, glucose 68 mg/dL, pH 7.38, WBC 2,200/uL with 85 percent lymphocytes, Ziehl-Neelsen stain negative. Adenosine deaminase in fluid is 58 IU/L. What is the most likely diagnosis?

• A Malignant pleural effusion
• B Parapneumonic effusion
• C Rheumatoid pleural effusion
• D Tuberculous pleural effusion ✓

Explanation

D lymphocyte-predominant exudate with high ADA (above 40 IU/L) in a young Indian adult is characteristic of tuberculous pleural effusion; ADA above 40 has high sensitivity and specificity in this setting. Parapneumonic effusions are neutrophil predominant with low pH and glucose. Rheumatoid effusions have very low glucose, usually below 30 mg/dL. Malignant effusions can be lymphocytic but typically occur in older patients and do not show such high ADA; cytology would be needed there.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.