False positivity of tumor markers in pleural fluid of traumatic hemothorax

Various biochemical parameters of pleural fluid have been employed to identify malignant effusions. However, many of them are also elevated in patients with nonmalignant conditions. We report on a patient with traumatic hemothorax, showing high pleural fluid concentrations of ferritin, tissue polypeptide antigen, and cancer antigen 125. This patient's pleural fluid also contained high levels of bilirubin and many macrophages containing phagocytized red blood cells, suggesting a local metabolism of hemoglobin. Our case confirms that some tumoral markers can give false positive results and suggests that their significance must be evaluated differently in bloody pleural effusions as compared with non-bloody pleural effusions.