Background <p>Pneumomediastinum with subcutaneous emphysema is an uncommon consequence of pediatric blunt thoracic trauma. Inferior extension of air into the scrotum (pneumoscrotum) is particularly rare, especially in the absence of pneumothorax.</p> Case presentation <p>A previously healthy 7-year-old boy presented 8 hours after sustaining blunt thoracic trauma from an ox kick directed to the left lower anterior chest. Swelling began within one hour and progressively extended from the face and neck to the chest, abdomen, and scrotum. Despite extensive cervicofacial, thoracoabdominal, and scrotal subcutaneous emphysema with diffuse crepitus, he remained hemodynamically stable without significant respiratory compromise. Hamman’s sign was present. Chest radiography demonstrated pneumomediastinum with the continuous diaphragm sign and extensive subcutaneous emphysema, without pneumothorax. Computed tomography confirmed pneumomediastinum with air tracking along bronchovascular sheaths consistent with the Macklin effect, retroperitoneal extension, and a focal pulmonary contusion. No tracheobronchial or esophageal injury was identified. The patient was managed conservatively with observation, analgesia, activity restriction, and supplemental oxygen. Complete resolution occurred within 7 days.</p> Conclusions <p>Extensive subcutaneous emphysema with pneumoscrotum can occur following pediatric blunt thoracic trauma via the Macklin effect without pneumothorax. Recognition of this pattern and correlation with clinical stability allows safe conservative management and avoidance of unnecessary invasive interventions.</p>