P2.N264: Where is the pneumonia? A child with isolated pleural effusion secondary to tuberculosis.

Introduction: Tuberculosis is a widespread disease affecting children globally. In children, the most common site of extrapulmonary tuberculosis is the lymphatic system. An isolated infection of the pleura with pleural effusion is much less described. We describe a patient with a massive left pleural effusion without the typical involvement of lung parenchyma.

Case Description: A 9-year-old vaccinated female with no significant medical history presented with a 3-day history of fever, dyspnea, and perioral cyanosis. She was hypoxic at presentation, but appeared comfortable on room air with decreased breath sounds on the left. She was born in Honduras and had received the Bacillus Calmette Guerin vaccine. Chest x-ray showed a large pleural effusion with mediastinal shift.

Labs were unremarkable including normal WBC count and negative or mildly elevated inflammatory markers. Chest ultrasound showed a simple large left pleural effusion which was re-demonstrated on CT. There was compression of lung tissue with rightward mediastinal shift, but an unusual lack of parenchymal involvement.

Interventional radiology was consulted and placed a left thoracostomy tube after which 1750 mL of serous fluid was removed. Pleural fluid showed nucleated cells of 1118/ mm3, with lymphocyte predominance, LDH of 276 u/L, and glucose of 89 mg/dL, consistent with exudative effusion. She was given empiric ceftriaxone and vancomycin, and infectious disease was consulted. Further work up showed negative MRSA PCR nasal swab, negative pleural fluid pneumococcal antigen, and no malignant cells. Mycobacterium tuberculosis PCR of sputum was negative. Daily chest x-rays showed progressive improvement, correlating with ongoing clinical improvement. Antibiotics were de-escalated and the chest tube was removed. Her QuantiFERON tuberculosis test returned positive and PPD was reactive.

The patient started four-drug therapy with rifampin, ethambutol, isoniazid, pyrazinamide, with added pyridoxine. Antibiotics were discontinued. Human immunodeficiency virus test was negative. Pleural fluid was negative for M. tuberculosis by PCR. She was discharged home with infectious disease follow-up. All cultures including tuberculous and non-tuberculous Mycobacteria, fungi, and bacteria were finalized negative.

Discussion: This case highlights the less frequent isolated pleural tuberculosis. The patient originally responded to antibiotics, mimicking atypical or community-acquired pneumonia. Further work-up revealed a negative M. tuberculosis pleural fluid PCR, but a positive QuantiFERON TB test and reactive PPD, pointing to M. tuberculosis as the causative agent.

Tests for M. tuberculosis in general are less sensitive in children than in adults requiring a higher degree of clinical suspicion. It is important to consider M. tuberculosis with finding of pleural effusions even in the absence of cough, pneumonia, or other classic pulmonary findings.

Conclusion: Clinicians should maintain a high index of suspicion for tuberculosis when treating pleural effusions even in the absence of classic symptoms or typical lung lesions.