術中胸腔内洗浄細胞診で陽性を示した上皮内肺腺癌

Pulmonary Adenocarcinoma in Situ with Positive Findings in Pleural Lavage Cytology

胸部CTで100％すりガラス陰影（pure ground-glass nodule：pure GGN）を呈する上皮内肺腺癌（adenocarcinoma in situ：AIS）は予後良好な肺癌とされている1，2）．われわれは，30 mm径のpure GGN，AISで切除前の術中胸腔内洗浄細胞診が陽性であり，術後1年6ヵ月で胸膜播種の再発をきたした症例を経験したので報告する．

We report a rare case of positive findings in pleural lavage cytology （PLC） in the patient with pulmonary adenocarcinoma in situ （AIS）. A 78-year-old woman was presented with a 30 mm pure ground-glass nodule （GGN） in the left upper lobe on chest computed tomography （CT）. After 2 years follow-up, thoracoscopic surgery was performed to resect the nodule. PLC was performed before pulmonary resection. Histopathological diagnosis was 25 mm AIS. However, PLC showed positive findings of malignant cells. CT examination at 1 year and 6 months postoperatively showed pleural dissemination findings and the patient died of lung cancer at 3 years and 2 months postoperatively. PLC’s contribution to TNM staging has not yet been clarified. The positive findings in PLC and large size of pure GGN were considered likely to be poor prognostic indicators.