Nonepithelial malignancies mimicking primary carcinoma of the breast

Although primary carcinomas account for the majority of breast malignancies, nonepithelial malignancies form a subset that must be differentiated accurately for treatment purposes. The purpose of this study was to identify cytological characteristics that differentiate between these two entities. Twenty-six fine-needle aspiration (FNA) specimens with histological correlation were reviewed (five lymphomas, two myelomas, six sarcomas, seven melanomas, and six carcinomas). On review, nonepithelial tumors presented as single cells with scant or ill-defined cytoplasm with rare cluster formations present. In contrast, carcinomas were arranged predominantly in clusters and contained more-defined, abundant, and sometimes vacuolated cytoplasm. Moreover, a major aid to diagnosis was an accurate clinical history. We conclude that nonepithelial malignancies of the breast are best differentiated from epithelial malignancies by a combination of cytological features and clinical information. These findings emphasize the importance of the triple test, in which integration of cytological findings and clinical information play a key role.