頭蓋底部に生じる軟骨肉腫と脊索腫とは画像所見や病理組織所見が非常に似ているため, 鑑別が困難な事がしばしばあります。 今回私たちは頭蓋底軟骨肉腫について染色体コピー数異常, isocitrate dehydrogenase(IDH)遺伝子突然変異, brachyuryタンパク質の発現を調べ, 脊索腫のそれらと比較をしました。 その結果, 軟骨肉腫において高頻度でIDH1遺伝子の突然変異を認めたの対し, 脊索腫では認めませんでした。また脊索腫で多く見られるbrachyuryタンパク質の発現は軟骨肉腫では認めませんでした。今回の結果から, これらの検査が鑑別において非常に有用であると考えられました。
Although chondrosarcomas rarely arise in the skull base, chondrosarcomas and chordomas are the two major malignant bone neoplasms occurring at this location. The distinction of these two tumors is important, but it is occasionally problematic because of radiological and histological overlap. We analyzed seven skull base chondrosarcoma specimens for chromosomal copy number alterations (CNAs), isocitrate dehydrogenase (IDH) 1/2 mutations and brachyury expression. We detected CNAs in six of the seven cases, including chromosomal gains of 8q21.1, 19. Mutation of IDH1 was found with a high frequency, of which R132S was most frequently mutated. Immunohistochemical staining for brachyury was negative in all cases. To the best of our knowledge, this is the first whole-genome study of an SBSC case series. Our findings suggest that these tumors are molecularly consistent with a subset of conventional central chondrosarcomas and different from skull base chordomas.
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