Evaluation of nipple secretions

A nipple discharge may be unilateral or bilateral; unilateral ones are more likely to be malignant. The secretion can be milky, serous, purulent or bloody. Cancer is most prevalent when the discharge is macroscopically bloody.

Benign nipple secretions - cytologic diagnostic features

• Usually sparsely cellular
• Ductal cells
• Foamy cells
• Inflammatory cells
• Red blood cells

Benign ductal cells are molded around one another and arranged in tight clusters, which can be small and spherical or large and branching; isolated cells are very uncommon. The cells are usually small, with scant cytoplasm, but sometimes they are larger with abundant cytoplasm. Foamy cells are histiocytes with abundant vacuolated cytoplasm and round or oval nuclei. When the secretion contains several groups of benign ductal cells, especially in large, branching clusters, an intraductal papilloma or a florid intraductal hyperplasia are likely to be present. These lesions can only be distinguished histologically.

Malignant nipple secretions - cytologic diagnostic features

• Clusters and single enlarged ductal cells
• Nuclear pleomorphism
• Stripped nuclei
• Nucleoli
• Acute inflammation
• Blood
• Necrotic debris