Recurrent Pleural Effusion Due to Duropleural Fistula

A 76-year-old woman with history of multiple spinal surgeries was found to have chronic recurrent pleural effusion. Thoracentesis was performed, which showed a clear, "water-like" transudative fluid with a total protein level of 0.2 g/dL, glucose level equivalent to serum (118 mg/dL), low LDH level (76 U/dL), and low nucleated cell count. Given the appearance of the fluid, β-2-transferrin was checked, which confirmed the presence of cerebrospinal fluid in the pleural space. On the basis of the clinical presentation, pleural fluid analysis, clear appearance of the pleural fluid, and β-2-transferrin positivity, the patient was diagnosed with duropleural fistula.