A case of postoperative pyopneumothorax following CT-guided radiofrequency ablation for lung cancer with interstitial pneumonia
The patient was a 67-year-old man with cT1bN0M0 non-small-cell lung cancer complicated with mild interstitial pneumonia. Prior to referral to our hospital, he had been under observation at the referring hospital for idiopathic pulmonary fibrosis/usual interstitial pneumonia for 1 year, during which a nodule of 2 cm was detected in the superior segment of the right lower lobe (S6) by chest computer tomography (CT) in May 2010 but remained undiagnosed even after additional bronchoscopy. At our center, pulmonary rehabilitation and oxygen inhalation at 3 l/min on exertion were started on an inpatient basis. Despite another diagnostic bronchoscopy, diagnosis was not made until September 2010 when CT-guided biopsy was performed. Non-small-cell lung carcinoma was diagnosed based on the biopsy results and staged as cT1bN0M0, as no metastasis was detected by contrast-enhanced CT and fluorodeoxyglucose positron emission tomography. Because the patient was considered at high risk for surgery, chemotherapy, and radiotherapy due to the complication with usual interstitial pneumonia and did not wish to undergo high-risk treatment, RFA was considered as an option.\nAfter review and approval by the institutional review board of Osaka City University Graduate School of Medicine and obtaining informed consent from the patient and his family, CT-guided lung RFA was performed in October 2010 (). Arterial blood gas measurements were: pH 7.41; PCO2 44; PO2 59.7; HCO3\n− 27.9; and SaO2 90.7 in room air. Pulmonary function test results were as follows: total lung capacity 6.15 l (percentage predicted total lung capacity 89.6%), total vital capacity 5.37 l (percentage predicted total vital capacity 87.3%); vital capacity 2.99 l (percentage predicted vital capacity 89.5%); forced expiratory volume in 1 s (FEV1.0) 2.71 l (percentage predicted FEV1.0 90.6%) and diffusion capacity for carbon monoxide 7.09 mL/min/mmHg (percentage predicted diffusion capacity for carbon monoxide; 43.8%). After subcutaneous and subpleural local anesthesia, the 2-cm lesion in the right S6 was punctured with a 17-gauge LeVeen Needle Electrode (array diameter of 3 cm, Boston Scientific, Natick, MA, USA) under CT guidance. 0.2 mg of fentanyl and 7 mg of midazolam were used in combination for analgesia and sedation, respectively. Electric current was applied to the tumor four times, starting at 30 W and then increasing by 5 W every 2 min. When the maximum resistance was reached, the current automatically stopped (“roll off”) indicating the completion of treatment. Ablation was applied for a total of 59 min and 37 s. The tumor was contained within the ablation range of the electrode, and a safety margin was considered achieved. Postoperatively, a prophylactic antibiotic was administered intravenously (Cefamezin, 1 g BID for 3 days). Only a small amount of hemoptysis was observed, and postoperative fever did not develop. Minor pneumothorax was indicated by CT after 2 days, but the patient did not exhibit dyspnea nor require oxygen administration at rest. The patient was discharged 3 days after RFA.\nChest X-ray and clinical follow-up after discharge, 2 weeks after RFA, revealed no pneumothorax requiring evacuation, dyspnea on exertion or other respiratory symptoms. Pulmonary rehabilitation was restarted as an outpatient basis. Progression of pneumothorax was evident on CT performed at 4 weeks after RFA. The patient was rehospitalized for aspiration via a 4 Fr chest tube. Pneumothorax improved, but the patient complained of back pain, and the tube was removed 5 weeks after RFA and continued administration of the antibiotic. Symptoms improved for 4 weeks, but the fever and back pain reappeared and elevated C-reactive protein and white blood cell count were observed. CT showed pleural effusion with an air-fluid level 12 weeks after RFA. Therefore, video-assisted thoracoscopic debridement of empyema and drainage were performed 13 weeks after RFA (). Necrosis of the S6 tumor was confirmed during the procedure. 24Fr conventional double lumen drain and 19Fr silastic flexible drain (BLAKE silicone drain; Ethicon, Somerville, NJ, USA) were inserted. Exudative pleural effusion cytology and cell culture tests were both negative. Because the control of air leak was poor even with debridement and drainage, 4 mL of a tissue adhesive (Bolheal, Kaketsuken, Kumamoto, Japan) and two times of autologous blood were administered. The air leak and fever finally subsided 24 weeks after RFA, and the drain was removed. Even though evidence of pleural effusion and pneumothorax was still detectable on CT, the patient did not present associated symptoms and was discharged 7 months after RFA. Follow-up CT at 11 months after RFA showed no signs of pleural effusion, though pneumothorax was still detected. No local recurrence or metastasis of the RFA-treated tumor was seen.