[Cytology and cytometry of breast cancer]

The cells of mammary carcinoma are obtained by means of fine-needle aspiration (FNA) and assessed by light microscopy. The cytologic diagnosis is supplemented by a steadily increasing series of various cytologic methods such as cytometry (morphometry and flow cytometry) as well as immunocytochemistry. This article deals with the basic principles of a correct FNA technique, its sources of error, and the pitfalls of cytologic differential diagnosis. The additive methods and some of their applications are presented briefly.