Table 3.

Distinguishing histological features of malignant spindle cell breast lesions

Tumour	Malignant phyllodes tumour	Spindle cell metaplastic breast carcinoma	Breast sarcoma
Epithelial component	Benign; distinct leaf-like pattern	Malignant	Absent
Ductal carcinoma in situ	Usually absent	May be present	Usually absent
Squamous differentiation	Usually absent	May be present	Absent
Heterologous differentiation	May be present	May be present	Tumour-specific differentiation
Broad-spectrum cytokeratins	Usually negative (−/+) in spindle cells	Invariably positive (+/−) in spindle cells	Usually negative (−/+) in spindle cells
p63	Usually negative (−/+) in spindle cells	Usually positive (+/−) in spindle cells	Usually negative (−/+) in spindle cells