Pleomorphic adenoma of the breast initially misdiagnosed as metaplastic carcinoma in preoperative stereotactic biopsy: a case report and review of the literature.

Pleomorphic adenoma (PA) is a benign mixed tumor found commonly in the salivary glands but rarely in the breast. PA might be misinterpreted clinically and pathologically as a malignant tumor. The differential diagnoses include fibroadenoma, phyllodes tumor and metaplastic carcinoma. Metaplastic carcinoma is the most important entitiy with respect to differential diagnoses, as surgical overtreatment, i.e., mastectomy may be the result. We describe one of the first cases of PA initially misdiagnosed as metaplastic carcinoma (osteoid-chondroid type) in a preoperative stereotactic biopsy and review the literature regarding this entity.