食道悪性黒色腫とmelanosisの鑑別診断—特に平坦病変について

Differential Diagnosis of Malignant Melanoma and Melanosis in the Esophagus

要旨●早期の段階で悪性黒色腫を発見・診断・治療することは，予後の改善につながるため極めて重要である．発見および診断のためには深達度が浅い平坦型悪性黒色腫の内視鏡的特徴を知ることがポイントと考えられ，特にmelanosisとの鑑別が大切である．自験悪性黒色腫・melanosis症例より，通常内視鏡像では両者の色調，厚みや辺縁性状が鑑別点となる可能性があり，黒色腫では真に黒色調で墨汁に似た色調，全体的に若干の厚みを有し，多くは不整形を呈し比較的境界は明瞭であると考えられた．一方，melanosisにおいて色調は淡明かつ濃淡のある黒色・褐色調で，ほぼ平坦な病変内には樹枝状血管網が散見され，その境界は不明瞭なことが多い．NBI観察像では，血管はほとんど視認できないが黒色腫における拡張したdot状のIPCL様所見がmelanosisとの鑑別点になる可能性がある．

　It is extremely important to detect, diagnose, and treat malignant melanoma in the early stage to improve the prognosis. It is essential to understand the endoscopic characteristics of malignant melanoma with small and flat characteristics, in which the depth of tumor invasion is shallow with a point for detection and the diagnosis. It is particularly important to be able to differentiate this type of tumor from melanosis. The color, thickness, and marginal form of both may act as differentiation points on the endoscopic image ； for melanoma, the color was found to be similar to that of India ink（dark black）with a general thickness, and it was believed that the border was relatively clear. However, the color of melanosis was light black, different from that of melanoma, and the branching vessels were observed as a flat lesion with an unclear margin. With the NBI（narrow band imaging）observation image, most of the blood vessels could not be seen in both the lesions, but expanded dots depicting IPCL（intra-papillary capillary loops）seen in the melanoma may facilitate differentiation from melanosis.