Abstract
Cases of pneumatocele formation following pulmonary resection are increasingly reported, yet its underlying pathogenesis and optimal treatment remain unclear. Here, we present a case of pneumatocele perforation occurring immediately after thoracoscopic left lower lobectomy. A 66-year-old man was found to have a suspicious nodule in the left lower lung zone during a routine chest X-ray as part of a medical checkup. CT suggested lung cancer in the left lower lobe, prompting referral to our hospital for further evaluation and treatment. Contrasted CT imaging revealed a ground-glass nodule with a maximum diameter of 4.6 cm, including a 4 cm solid component, located in segments S9/10 of the left lower lobe. No signs of emphysema were observed, and pulmonary function tests indicated normal respiratory capacity. PET-CT showed mild uptake (SUVmax 2.04) in the left lower lobe mass, with no evidence of distant metastasis. Additionally, contrast-enhanced brain MRI showed no abnormalities suggestive of metastasis. Bronchoscopy was performed, but transbronchial lung biopsy and brushing/irrigation cytology yielded no evidence of malignancy. Based on these findings, stage IB primary lung cancer was suspected, and a surgical biopsy followed by lobectomy was planned. The procedure was conducted using a four-port, completely thoracoscopic approach. Intraoperative needle biopsy confirmed adenocarcinoma, leading to left lower lobectomy and mediastinal lymph node dissection. Immediately after chest wound closure, a large volume of air leakage was observed, along with pneumatocele formation and perforation on the mediastinal side of the upper lobe. The pneumatocele was incised, its base cauterized, and covered with a TachoSil(®) fibrin sealant patch (CSL Behring, King of Prussia, PA, USA). Postoperatively, a mild air leak persisted, requiring a single session of adhesive therapy. Lung fragility and increased negative intrathoracic pressure following resection are key risk factors for pneumatocele formation. While most cases can be managed conservatively, surgical intervention should be considered in symptomatic cases, particularly those presenting with pneumothorax or hemoptysis. If a pneumatocele develops intraoperatively, positive pressure ventilation and compression may cause further expansion. Therefore, we recommend prompt incision to prevent enlargement, followed by air leak closure through cauterization of the base and application of a sealing material.