Pancreatic pseudocysts are mostly located in the peripancreatic region, but extra-abdominal intrathoracic extensions can occur and mimic respiratory and ischemic symptoms. Mediastinal location is an example that can present with dyspnea and retrosternal chest pain. Pancreatic-pleural fistulas can form from pseudocysts, often resulting in large and recurrent pleural effusions. In the described case, a 50-year-old man with a previous subdiaphragmatic pseudocyst presented an acute episode of respiratory symptoms and was diagnosed with a newly organized collection located intrathoracically adjacent to the previous one, formed by the fistulization of the abdominal pseudocyst. No similar cases have been described or published in indexed PubMed databases until the year 2023.