Focal Anomalous Expression of Cytokeratin and p63 in Malignant Phyllodes Tumor: A Comparison With Spindle Cell Metaplastic Carcinoma

Differentiating between malignant phyllodes tumors and metaplastic spindle cell carcinomas could be problematic, especially on core biopsies. Immunohistochemical staining for cytokeratin cocktail and p63 has been utilized to differentiate between these tumor types. Forty-three phyllodes tumors (27 b