Histogenesis of benign pleomorphic mesenchymal tumours

Benign pleomorphic mesenchymal tumours (lipoma, fibroblastoma) are defined by large cells with multiple peripheral nuclei reminding of florets. Similar cells were previously detected by Mirejovský as a reactive phenomenon in polypous processes. We assume that these cells may occur not only in pseudotumours but also in tumours with stromal conditions similar to those in polyps. Therefore pleomorphic giant cell are of no value for assessment of the histogenesis of tumours. Nevertheless, the pleomorphic giant cell reaction is important in practice because it is not to be mistaken for tumorous atypia.