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Pleural Effusion — RACP Adult Medicine MCQ

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HardRespiratoryPleural EffusionRACP Adult Medicine

A 55-year-old with long-standing seropositive rheumatoid arthritis develops a unilateral exudative pleural effusion. Pleural pH is 7.10, glucose 1.2 mmol/L, LDH is very high, cultures are negative and cytology shows elongated macrophages without malignant cells. What is the most likely diagnosis?

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Correct answer: E — Rheumatoid pleuritis

The best answer is “Rheumatoid pleuritis”. Rheumatoid pleural effusions are exudative and characteristically have very low glucose and pH with high LDH. Infection must still be excluded urgently because empyema can produce the same chemistry; the rheumatoid history, sterile cultures and cytology support rheumatoid pleuritis here. Cardiac, hepatic and urinary causes are usually transudative or have different defining chemistry.

Reference: RACGP: Rheumatoid pleuritis: https://www.racgp.org.au/afp/2015/november/an-uncommon-cause-for-a-unilateral-pleural-effusio