Two Cases of Mediastinal Non-Seminomatous Germ Cell Tumor with Complete Resection by Robot-Assisted Thoracoscopic Surgery after Induction Chemotherapy: Techniques for Identification and Preservation of the Phrenic Nerve

Abstract

INTRODUCTION: Mediastinal non-seminomatous germ cell tumors (NSGCTs) are rare tumors. Neoadjuvant chemotherapy followed by complete surgical resection of residual masses is recommended, and is often performed through a median sternotomy or thoracotomy with regard to the influence of induction chemotherapy and tumor size. We herein report 2 cases of mediastinal NSGCT that were surgically resected by robot-assisted thoracoscopic surgery (RATS) using the subxiphoid approach.

CASE PRESENTATION: Case 1: A 23-year-old man was diagnosed with an anterior mediastinal mass measuring 95 × 73 × 73 mm while undergoing an examination due to fever. He was diagnosed with a yolk sac tumor based on percutaneous needle biopsy. After 4 cycles of neoadjuvant chemotherapy, the patient underwent tumor resection combined with wedge resection of the left upper lung via a robot-assisted subxiphoid approach. It was particularly difficult to identify the left phrenic nerve because of stiff adhesions and thickening of the tissue. Therefore, we decided to perform dissection of tissue other than that surrounding the left phrenic nerve. Subsequently, the thymus and tumor were flipped into the left thoracic cavity, and the left phrenic nerve was easily identified and preserved from the pericardial side. The patient was discharged without any postoperative complications. Case 2: An 18-year-old man was diagnosed with a yolk sac tumor measuring 86 × 68 × 150 mm during an examination to investigate intermittent right chest pain. After 4 cycles of neoadjuvant chemotherapy, the patient underwent anterior mediastinal tumor resection via a robot-assisted subxiphoid approach. The tumor was close to the right pulmonary hilum, and the inflammation was so intense that it was difficult to identify the right phrenic nerve. In this case, indocyanine green fluorescence imaging was helpful for identifying the right phrenic nerve. The tumor was completely resected. The patient was discharged on POD 6 without any postoperative complications.

CONCLUSIONS: We report 2 cases of mediastinal NSGCT after induction chemotherapy that were completely resected using RATS. The use of techniques to accurately identify the phrenic nerve and the advantages of robot-assisted surgery via the subxiphoid approach enabled safe and minimally invasive surgical procedures.