A Case of Lung Cancer Arising in an Intrapulmonary Brochogenic Cyst

Background. Bronchogenic cysts are commonly found in the mediastinum but also occasionally in the lung parenchyma. We herein report a rare case of lung cancer arising in an intrapulmonary bronchogenic cyst. Case. A 58-year-old woman with a smoking history developed a cough and hemosputum in April 2021. On an examination at a local hospital, no abnormal shadow was found on her chest radiograph, but computed tomography of the chest revealed a 6.4-cm pulmonary cyst with irregular wall thickness in the right lower lobe. Fluorodeoxyglucose-positron emission tomography showed abnormal accumulation in the thickened wall of the pulmonary cyst (maximum standardized uptake value: 4.22). The diagnosis based on sputum cytology was class IIIA, but lung cancer with cystic lesion could not be excluded. In September 2021, the patient underwent resection of the cystic lesion under thoracoscopic surgery. A frozen section obtained during surgery revealed adenocarcinoma, and video-assisted thoracoscopic right lower lobectomy was performed. Microscopic findings showed bronchogenic lung cysts and the proliferation of malignant cells along the cyst' inner walls (pT3N0M0). The patient was alive nine months after surgery without recurrence. Conclusion. Only 10 cases of lung cancer arising from intrapulmonary bronchogenic cyst have been reported in Japan. When carcinoma is suspected in the bronchogenic cyst, appropriate surgical procedures should be considered.