An 8-year-old male child presented to an emergency department with a 3-day history of asthenia, fever and cough. There was no history of recent weight loss. Findings on examination included: fever (38ºC or 100.4ºF), tachycardia, tachypnea and diminished breath sounds over the left hemithorax. The patient underwent radiographic evaluation.

Question:
Based on the clinical scenario and images provided, the most likely diagnosis is: