The WBC count was 7,600/μL, with a differential of 79% neutrophils, 10% lymphocytes, and 10% monocytes. The hemoglobin, platelet count, serum electrolytes, renal function, and urinalysis were all normal. The sedimentation rate was 33 mm/h. The chest radiograph revealed a large right pneumothorax and bilateral pleural effusions (Fig 1
). A chest tube was placed in the right superior hemithorax to re-expand the lung and obtain a sample of pleural fluid for analysis. The amber-colored fluid contained 3,700 WBCs/μL (with a differential of 46% neutrophils, 48% lymphocytes, and 6% monocytes). Chemistry studies revealed a glucose of 50 mg/dL, lactate dehydrogenase of 768 U/L (serum lactate dehydrogenase, 198 U/L), and protein of 5.0 g/dL (serum protein, 6.6 g/dL). Stains for acid-fast bacilli (AFB) and fungi were negative, and the Gram stain revealed 4+ WBCs but no organisms. Culture findings for bacteria were subsequently negative. The patient was admitted to the hospital.