Pneumothorax Ex Vacuo.

An 84-year-old woman with pleural effusion developed anterior chest pain during thoracentesis, and post-procedural chest radiography revealed hydropneumothorax, initially suggesting iatrogenic pneumothorax. However, comparison of pre- and post-procedure imaging showed ipsilateral hemithoracic volume loss with tracheal deviation toward the procedure side, supporting pneumothorax ex vacuo, managed conservatively without intervention.