A 26-year-old man presents with 3 weeks of low-grade evening fever, right-sided pleuritic pain and breathlessness. Chest radiograph shows a moderate right effusion. Pleural fluid: straw coloured, protein 4.6 g/dL, LDH 320 IU/L, glucose 78 mg/dL, pH 7.36, total cells 1800 per microlitre with 88% lymphocytes, adenosine deaminase 62 IU/L. What is the most likely diagnosis?

• A Tuberculous pleural effusion ✓
• B Complicated parapneumonic effusion
• C Rheumatoid pleuritis
• D Malignant pleural effusion

Explanation

A lymphocyte-predominant exudative effusion with adenosine deaminase above 40 IU/L in a young Indian adult is classical for tuberculous pleuritis, where ADA reflects activated CD4 T cell activity. Parapneumonic and rheumatoid effusions are neutrophil dominant with low glucose and low pH, while malignant effusions usually have ADA below 40 IU/L with mononuclear cells and often bloody fluid.

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

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Written and medically reviewed by the StethoPrep medical team.