喀癌細胞診陽性から発見された肺末梢発生小型扁平上皮癌の1例

摘要

背景．喀痰細胞診陽性から発見された肺末梢発生の小型扁平上皮癌の1例を報告する．症例．77歳男性．肺癌検診の喀痰細胞診で陽性と判定され精査を施行するも異常を認めなかった．2年後，胸部X線写真，胸部CTにて右S~3に径12mmの小型腫瘤影を認めた．気管支鏡検査にて可視範囲に異常所見を認めず，全支擦過細胞診を施行するも悪性所見は認めなかった．右S~3の腫瘤は6次分岐以降の末梢に存在するものと判断し，CTガイド下経皮生検を施行し，扁平上皮癌と診断され，60Gy/8回の定位放射線療法を施行した．治療後約4年経過したが，癌の再発は認めず，喀痰細胞診も陰性を持続している．結論．肺末梢発生の小型扁平上皮癌が喀痰細胞診陽性の原因と考えられた．Background. We report a case of a small lesion of squamous cell carcinoma of the peripheral lung diagnosed two years after sputum cytology indicated malignancy. Case. A 77-year-old man had positive findings on sputum cytology mass screening, but no abnormality was found on investigation. Chest radiography and computed to mography performed two years later revealed a 12mm nodule in the S3 segment of the right upper lobe. Bronchoscopy of the area that could be visualized and selective brushing cytology of each segmental bronchus were negative. The nodule was estimated to be located in the sixth bronchial branch or a more peripheral region, and percutaneous biopsy of the nodule aided by computed tomography was performed, resulted in a diagnosis of squamous cell carcinoma. He subsequently received stereotactic radiation therapy (60 Gy in 8 fractions). During four years of follow up, sputum cytology has continued to be negative. Conclusion. Positive findings on sputum cytologic examination in the present case were due to a small lesion of squamous cell carcinoma of the peripheral lung.