IntroductionPulmonary radiofrequency ablation (RFA) is one of thetreatment options for primary and metastatic lung tumorsand has had minimal procedure-related complications [1].The most frequent complication related to pulmonary RFAis pneumothorax [2]; mediastinal emphysema is rare. Thepatient may develop only subcutaneous and mediastinalemphysema, with little pneumothorax. This is a specificclinical condition.Here we describe a case of massive subcutaneous andmediastinal emphysema, with the patient developing littlepneumothorax after pulmonary RFA for metastatic lungtumors. The complication was treated by surgical sutureclosure of the fistula in lung parenchyma after an unsuc-cessful attempt to inject liquid embolization material undercomputed tomography (CT)-guided navigation.Case ReportA 56-year-old man was referred to our hospital for a sec-ond opinion regarding the treatment of recurrent metastaticlung tumors from esophageal carcinoma. He had a historyof pulmonary resection in bilateral lungs for metastatictumors. Because of limited pulmonary function, pulmonaryRFA was selected for the treatment of an 8-mm-diametertumor located immediately below the visceral pleura of theleft lung at the department of radiology in our hospital(Fig. 1A, B). Before pulmonary RFA, the creation of anartificial pneumothorax was tried for pain relief and pro-tection of the chest wall from thermal injury. However, itwas not successful as a result of pleural adhesion. Afterpulmonary RFA, CT scan revealed that subcutaneous andmediastinal emphysema with slight pneumothorax wasevident and progressively advanced, whereas pneumotho-rax improved (Fig. 1C). CT-guided injection of liquidembolization material into the fistula in lung parenchymawas attempted 6 days after the pulmonary RFA, but it wasunsuccessful. The patient’s voice gradually changed. Fol-low-up CT scan 10 days after the pulmonary RFA revealedthe possibility of the collapse of superior vena cava andsubsequent hypovolemic shock by progressive mediastinalemphysema (Fig. 1D).The patient was referred to the department of thoracicsurgery for a surgical procedure, and an emergent operationwas performed on the same day. There was moderate to