Recognizing the Macklin Effect in Patients with Persistent Vomiting: A Case Report of a Paratesticular Rhabdomyosarcoma

The Macklin effect is a rare but important cause of pneumomediastinum resulting from alveolar rupture and air dissection along bronchovascular sheaths, often triggered by forceful vomiting. We report a 17-year-old male with high-risk paratesticular embryonal rhabdomyosarcoma who underwent placement of an uncovered metallic duodenal stent for malignant obstruction. Persistent tumor-related duodenal obstruction led to repeated vomiting, and follow-up contrast-enhanced CT demonstrated pneumomediastinum with linear air tracking along bronchovascular bundles, consistent with the Macklin effect. Concurrently, CT revealed significant retroperitoneal tumor progression and tumoral ingrowth into the duodenal stent, explaining continued gastric outlet obstruction. This case highlights the importance of recognizing the Macklin effect in oncologic patients with persistent vomiting, differentiating it from esophageal perforation, and underscores the central role of CT in evaluating both abdominal tumor progression and secondary thoracic complications.