Massive malignant pleural effusion due to lung adenocarcinoma in 13-year-old boy.

A 13-year-old boy with no risk factors for lung cancer presented with a massive left-sided pleural effusion and a mediastinal shift on chest radiography and computed tomography. A chest tube drained bloody pleural fluid with an exudative pattern. A pleural biopsy and wedge biopsy of the left lower lobe revealed mucinous adenocarcinoma in the left lower lobe wedge biopsy and metastatic adenocarcinoma in the pleural biopsy. The patient is currently undergoing chemotherapy. Radiotherapy is planned after shrinkage of the tumor. Adenocarcinoma of the lung is very rarely seen in teenagers or children, especially in the absence of risk factors.