A 70-year-old man with no symptoms and a history of diabetes mellitus and subsequent chronic kidney disease was referred to our hospital because an abnormal lung nodule had been detected by chest computed tomography (CT). Initially, the CT image revealed a pure ground-glass nodule that was thought to be benign (Figure 1A). During 6 months of close follow-up, the nodule gradually developed a solid component. CT finally showed a part-solid ground-glass nodule measuring 22 mm (the solid component measured 8 mm) in the left apicoposterior segment (S1+2), which raised suspicion for malignancy (Figure 1B). 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) showed hypometabolic activity (maximum standardized uptake value, 1.4). Distant metastases were not detected by whole-body CT or FDG-PET. The patient was referred to our department for surgical treatment.
The preoperative CT scan showed a displaced anomalous B1+2 branching from the left main bronchus behind the left main pulmonary artery (Figure 2A, B). The patient was suspected to have early-stage lung cancer (cT1aN0M0-IA1) located in S1+2 with a left displaced anomalous B1+2.
Considering the patient’s comorbidity, we decided to perform left S1+2 segmentectomy. The surgery was conducted under four-port VATS. The displaced B1+2 was initially accessed by dissecting along the posterior side of the mediastinal pleura. We identified the displaced B1+2 and subsequently detected A1+2 branching along the displaced B1+2 from the left main pulmonary artery. After dissecting the hilar lymph nodes, the displaced B1+2 and A1+2 were exposed and cut respectively with a mechanical stapler (Figure 3A). Several lymph nodes were analyzed by intraoperative frozen section and found to be negative for metastasis. Indocyanine green (ICG) was administered intravenously. The intersegmental plane was identified under near-infrared thoracoscopy. The surface of the whole left lung except that of the target segment turned green (Figure 3B). In addition to the intersegmental plane, we identified the actual location of the tumor with the aid of palpation thoracoscopically. Following the intersegmental plane suggested by systemic ICG injection and after confirming the tumor location, we completed left S1+2 segmentectomy with the use of mechanical staplers. After obtaining the specimen, we reconfirmed intraoperatively that the surgical margin was tumor-free. The operation time was 130 minutes, and the blood loss was minimal. The postoperative course was uneventful, and the patient was discharged 4 days after surgery.
The pathological diagnosis was invasive adenocarcinoma. The dimension of tumor invasion was 16 mm. The surgical margin was negative and all lymph nodes were negative for metastases. The pathological stage was p-T1bN0M0. At the time of this writing (8 months postoperatively), the patient was alive without recurrence.