This case report presents an intrapulmonary bronchogenic cyst exhibiting a unique shape. The patient was a 19-year-old man who had been diagnosed with a posterior mediastinal tumor by computed tomography and magnetic resonance imaging, 2 years previously. The imaging revealed that the tumor was located on the left side of the posterior mediastinum and was 45 × 25 mm in size. As the size and shape of the tumor did not change in the 2 years after its detection, surgical extraction was planned. Preoperative diagnosis was, firstly, a neurogenic tumor originating in the posterior mediastinum.Surgical findings revealed that the tumor formed a bridge between the visceral pleura of the left lower lobe and the chest wall, and most of the tumor was located in the thoracic cavity. Pathological diagnosis was intrapulmonary bronchogenic cyst. An intrapulmonary bronchogenic cyst with a unique shape, as observed in this case, is very rare.Although preoperative imaging could predict the tumor size, it could not confirm where the tumor originated. Surgical resection of this type of tumor, which is diagnosed preoperatively as a posterior mediastinal tumor, is a superior strategy for precise diagnosis and treatment.