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- FIGURE 7-2. The origin of biological heterogeneity in primary
- neoplasms and metastases. Biological heterogeneity in tumors that are
- unicellular in origin is due to genetic and epigenetic instability. By
- the time of diagnosis, most neoplasms consist of multiple
- subpopulations of cells with different properties. Metastases can have
- a clonal origin and different metastases can originate from different
- progenitor cells. Even in clonal metastases, biologic diversification
- gives rise to heterogeneous lesions.
-