Clinical decision-making in atypical and suspicious categories in fine-needle aspiration cytology of the breast

Backgroud: Fine-needle aspiration cytology (FNAC) is a simple and reliable technique to assess breast lesions, although a definitive differential diagnosis (benignity vs. cancer) is achieved approximately in 60-70% of cases because an inadequate (C1), atypical (C3) or suspicious (C4) category is otherwise reported. Patients and Methods: A retrospective analysis of 763 cases with C3 or C4 reports was performed to define their positive predictive value (PPV), as well as the practical implications of clinical and imaging findings as for clinical decision-making. FNACs were collected from January 2003 to September 2012 at the Breast Unit of IRCCS "A.O.U. San Martino-IST" Genoa, with each being received later to definitive histology. The PPV for cancer of C3/C4 categories were computed to measure the accuracy of FNAC; moreover, the PPV was also stratified according to clinical, mammography and sono graphy data alone or by their combination. Resuls: The PPV of C3 and C4 was 21.1% (80/380) and 84.1% (322/383), respectively. Within each C3/C4 category, a significant direct correlation (p