Fibroadenoma

Fibroadenoma is the most common breast neoplasm, occurring in all age groups, but especially common in young women from 20 to 35 years of age. In contrast with the ill-defined nature of fibrocystic change, fibroadenomata are movable, discrete nodules, measuring usually less than 4 cm in maximum dimension. They often increase in size with pregnancy because of lactational changes.

Cytological diagnostic features

• High cellularity
• Tightly cohesive, flat, honeycomb sheets and three -dimensional aggregates
• Finger-like branching and stag horn-like epithelial clusters
• Numerous bipolar naked nuclei
• Fragments of fibrotic, sometimes fibro-myxoid stroma
• Apocrine and foamy cells can occasionally be present
• Occasional epithelial atypia

Aspirates from fibrocystic change and fibroadenomata show the same range of cytological features. However, the clinical findings and the mammographic picture are usually quite different. FNAs of fibroadenomata can be a source for false-positive diagnoses of malignancy, particularly when hypercellular smears show loose epithelial cohesion, which can be an artefact of vigorous smear preparation, and epithelial atypia. The presence of naked nuclei should suggest the benign nature of the lesion, along with the clinical and mammographic picture.