Pleomorphic Adenoma of the Breast: Cytology of Fine-needle Aspiration and Its Differential Diagnosis

The cytologic findings of a case of pleomorphic adenoma of the breast are presented. This rare tumor appeared identical to pleomorphic adenoma of salivary glands. It presented diagnostic difficulties, however, because of its rarity and the fact that its associated clinical findings suggested a malignancy. The cytologic differential diagnosis includes a phyllodes tumor, fibroadenoma, and metaplastic carcinoma. Awareness of this entity should permit a definitive diagnosis by aspiration biopsy.