Myoepithelial cells in needle aspirations of two cases of unusual breast lesions: an aid in differential diagnosis.

The observation of myoepithelial cells bordering abnormal epithelial cells in fine-needle aspiration smears of two unusual breast lesions helped to prevent misdiagnosis of these lesions as malignant. The presence of myoepithelial cells has been a well-established criterion for histologically benign lesions. Their presence or absence appears to be equally valuable in fine-needle aspiration smears of breast lesions.