[Cystosarcoma phyllodes and sarcoma of the breast].

Altogether 217 phyllode tumours, 28 sarcomas and 5 carcinosarcomas of the mammary gland have been studied in the Institute from 1946 to 1980. Three structural variants of phyllode tumour are distinguished: 1) early stages of formation, 2) classical phyllode tumour, 3) phyllode tumour with sarcomatous stroma. 20 out of 28 sarcomas are linked with phyllode tumours while the morphogenesis of primary sarcomas, which are characterized by a more malignant clinical course, remains unclear. When studied electron-microscopically, classical phyllode tumour reveals marked and peculiar vascular proliferation which not infrequently coincides with cellular stroma. Various directions of functional and structural differentiation of stromal cells are observed. The alternation in the tumour of areas with different morphology found in light microscope is reflected by the dependence of the structure of intercellular substance upon the type of stromal cells observed electron-microscopically.