only 15 cases of such tumors have been reported in the English literature, variously described as cystadenoma, cystomyoma, low-grade phyllodes tumor, benign mesenchymoma, adenomyosis, and ...

While the majority of phyllodes tumors are non-cancerous, the Cleveland Clinic notes that about 25% are cancerous. Cancerous phyllodes tumors account for a mere 0.05% of all breast malignancies.