Papillary neoplasms of the breast: clues in fine needle aspiration cytology.

Papillary neoplasms of the breast include a wide spectrum of mammary lesions. The differential diagnosis of benign and malignant lesions can be problematic not only cytologically, but also histopathologically. Aspiration smears can demonstrate that cytological differentiation is feasible. A retrospective study of 30 cases of papillary tumour of the breast, 15 papillary carcinomas and 15 papillomas, was performed to find the cytological differences between the pathologies. Cytological samples of papillary carcinomas were characterized by an abundance of cellular material, three-dimensional papillary clusters without fibrovascular connective tissue cores, small papillae arranged in cell balls, tall columnar cells and isolated naked nuclei. Numerous haemosiderin-laden macrophages were seen. There were no eosinophilic bipolar cytoplasmic granules, bipolar naked nuclei or apocrine metaplasia. In the papillomas there was less material; the papillae had cohesive stalks surrounded by columnar cells in a honeycomb pattern. We also found fewer small papillae and isolated columnar cells. In addition, the presence of apocrine metaplasia and bipolar naked nuclei was noted. We suggest that papillary carcinoma of the breast can be diagnosed by cytology and differentiated from papilloma.