大腸腺腫とDNA

A Microspectrophotometric Study of Colorectal Adenomas

要旨　54個の大腸腺腫の核DNA ploidy patternを落射型顕微測光法により分析した結果，diploid＋polyploid patternを9個（17％），aneuploid patternを7個（13％）に認めた．これら2つのploidy patternの出現頻度は腺腫の異型度が高いほど，病変の大きさが大きいほど高率であった．特に構造異型が発現していないmoderate atypiaの中にaneuploid patternを呈するものが認められたことは，核DNA ploidy patternの解析が大腸腺腫の異型度分類の新たな指標になりうることが示唆された．組織切片による核DNA量の測定は，異型度と正確に対応した測定が可能でありスメア法あるいはフローサイトメトリーの短所を補うものとして価値があると考えられた．

　Nuclear DNA contents of 54 colorectal adenomas were analyzed with microspectrophotometry and their histograms were classified into diploid, diploid plus polyploid, and aneuploid patterns. These included 29 adenomas with mild atypic,13 with moderate atypia and 12 mucosal carcinomas. Relationship between histological atypia and ploidy patterns was investigated with special attention to the borderline lesions (adenomas with moderate atypia) .

　Diploid plus polyploid patterns were detected in 9 adenomas (17%) and aneuploid patterns in 7 (13%) . In mild atypia, diploid plus polyploid and aneuploid patterns were detected in 10%, 0%; 23%, 31% in moderate atypia ; 25%, 25% in mucosal carcinomas respectively.

　The higher the grade of atypia, the higher the frequency of diploid plus polyploid/aneuploid patterns with statistical differences. The results of some adenomas with moderate atypia showing aneuploid patterns suggested that the measurements of nuclear DNA contents could be a new clue in classifying grade of atypia of colorectal adenomas.

　As colorectal adenomas are frequently made up from various atypical glands, the measurement of nuclear DNA content in 4～7μm thick specimens facilitates site to site analysis of grade of atypia and is a better method than flow cytometry for this purpose.