Ductal adenoma of the breast: the cytological features of six cases.

Ductal adenoma of the breast may simulate malignancy by both clinical, histological, and cytological examination. Fine-needle aspirations from breast lesions are now daily routine and preoperative recognition of this benign lesion is desirable. This study describes the cytologic features of six additional cases of ductal adenoma. The smears from all the lesions were highly cellular with epithelial cells in sheets. Numerous large fragments of purple stroma in tight connection with epithelial cells often making finger-like hyaline structures or globules between cells were seen. Naked oval nuclei in the background were observed in all cases indicating benignancy. We find the cytologic picture in fine-needle aspirations from ductal adenomas sufficiently characteristic for preoperative diagnosis. The differential diagnoses toward other benign and malignant conditions are discussed.