Phyllodes tumour and stromal sarcoma of the breast: an ultrastructural comparison.

The ultrastructure of the stromal cells of three benign and one malignant phyllodes tumours and three stromal sarcomas has been studied and compared with the stromal cells of two fibroadenomas and four normal lobules. One stromal sarcoma was possibly of nerve sheath origin, but the other two showed features in common with the phyllodes tumours and the fibroadenomas. Prominent electron dense cytoplasmic bodies with distinctive morphological features are described and a correlation with the degree of malignancy is postulated.