Cytomorphology of common malignant tumors of the breast.

A definitive cytologic diagnosis of breast cancer is usually possible when using the six major criteria of malignancy (cellularity, dyshesion, monomorphism, anisonucleosis, irregular nuclear membranes, prominent nucleoli) as part of the triple test. Carcinomas of special type have unique clinical and cytologic features that pathologists need to consider, because these may confuse interpretation. Complete subtyping of carcinomas may not always be possible by fine needle aspiration. Diagnostic accuracy for breast carcinoma is excellent. False-negative diagnoses are infrequent and chiefly due to sampling issues. False-positive diagnoses are extremely rare. Uniform report terminology should be used to ensure that diagnostic information is conveyed appropriately and consistently to guide the next diagnostic or treatment step.