RESUMEN
Empyema necessitatis, which is a rare complications of empyema especially in immunocompromised conditions, extends pus from the thoracic cavity into surrounding soft tissues. The causes of empyema necessitatis are fungal infection, pulmonary tuberculosis and various types of pneumonia. A 9-year-old boy presented with a 7 day history of anterior chest pain and a coin sized palpable mass. Physical examination revealed a papable egg sized erythematous mass above the areola of the left chest. Laboratory data revealed acute inflammation. CT scans of chest demonstrated acute inflammation from the left anterior chest to the mediastinum and pericardium. He underwent sono guided thoracentesis and percutaneous aspiration of the mass and no organisms grew in a culture of pleural fluid and percutaneous aspiration. Tuberculin skin test was negative. The child was treated with antibiotics. Then, pain and the size of the mass decreased, follow up results of CT were resolved and he was discharged with oral antibiotics. We experienced a rare case of empyema necessitatis in 9-year-old child who was immunocompetent.