Pleomorphic adenoma of the breast: case report and review of the literature.

Pleomorphic adenoma of the breast (PAB) is a very rare neoplasm. Although quite unique in its morphology, PAB shares some similarities with adenomyoepithelioma and is considered by some authors as a variant of this entity. Cytologic diagnosis of this lesion can be very challenging, especially when limited sampling is available. The differential diagnosis of PAB includes metaplastic carcinoma. On cytologic material, fibroadenoma and phyllodes tumor should also be considered within the differential diagnosis. We report the findings in a case of PAB, initially misdiagnosed as mucinous carcinoma on fine-needle aspiration, and review the literature regarding this entity. Correct identification of this benign mammary neoplasm is important to avoid unnecessarily aggressive treatment. Copyright 2005 Wiley-Liss, Inc