Which ideas about malignant tumors proposed by Rudolf Virchow were later shown to be incorrect?

While Rudolf Virchow is celebrated for grounding cancer research in cell biology and establishing that tumors are composed of cells, his work on malignant tumors contained a significant error.12

In his three-volume work Die krankhaften Geschwülste (1863–67), Virchow proposed that malignancy resulted from a conversion, or metaplasia, of connective tissue. This hypothesis was later shown to be incorrect, as it did not accurately reflect the origins of malignant processes.2

Despite this specific misconception, Virchow’s broader application of cell theory—specifically the principle that cells arise from preexisting cells—remains a cornerstone of modern pathology and helped overturn earlier, erroneous theories regarding the nature of disease.123