这个词是什么意思？
A true neoplasm composed of a number of different types of tissue, none of which is native to the area in which it occurs. It is composed of tissues that are derived from three germinal layers, the endoderm, mesoderm, and ectoderm. They are classified histologically as mature (benign) or immature (malignant). (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1642)
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D013724 · MeSH 2026。
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