Atypical ductal hyperplasia

Intraductal epithelial proliferations of the breast represent a spectrum ranging from intraductal hyperplasia without atypia (conventional ductal hyperplasia) to atypical ductal hyperplasia (ADH), to ductal carcinoma in situ (DCIS).

Conventional hyperplasia can be mild, moderate or florid, depending on the degree of epithelial proliferation. Aspirates show increased cellularity, with cohesive epithelial groups and bipolar naked nuclei. Some variations in cell size and shape can be present within the groups, but single atypical epithelial cells are not seen.

Aspirates of ADH are usually highly cellular and contain crowded groups of cells with both bland and atypical features.

Cytological diagnostic features of ADH

• High cellularity
• Considerable cellular and nuclear overlapping
• Cellular monotony
• Prominent nucleoli
• Myoepithelial cells within the groups and stromal bipolar naked nuclei in the background

The cells show considerable variation in cell size and shape and some loss of polarity within the groups. Occasional single atypical cells can be present, however, in contrast with DCIS, bipolar naked nuclei are present.

Cytology is not usually believed to be reliable in sub-classification of proliferative breast disease. Aspirates deemed to be 'atypical' should lead to surgical biopsy.