Role of sample adequacy in fine needle aspiration biopsy of palpable breast lesions

Background: The role of fine needle aspiration biopsy (FNAB) in breast lesi ons remains uncertain because its accuracy has been questioned. We hypothes ized that this is related to failure to define standards for adequacy of sa mple preparation, Methods: We reviewed cytology and pathology reports from 351 patients under going FNAB at a 350-bed community, university-affiliated teaching hospital over a 2-year period. Patients were included if they had an open biopsy wit hin 2 years of an FNAB of the same lesion. Cytology reports were reviewed b y a cytopathologist unaware of the clinical setting or subsequent histology ; surgeons unaware of the cytology reports reviewed histology reports. Cyto logical diagnoses were benign, likely benign, probable cancer, and definite cancer. Samples were characterized as satisfactory, less than optimal (few mammary epithelial clusters), or inadequate (no mammary epithelial cluster s.) We assessed the proportion of inadequate samples, the accuracy of FNAB, and the influence of sample adequacy upon FNAB sensitivity. Results: Ninety-nine (28%) FNABs were inadequate, 77 (22%) less than optima l, and 175 (50%) satisfactory. Ninety-five patients (27%) had a final diagn osis of malignancy. FNABs classified as satisfactory or less than optimal a nd characterized as benign (n = 102) had a negative predictive value (NPV) of 0.91; those termed definite cancer (n = 43) had a positive predictive va lue (PPV) of 0.98. Only 10% of all cancers were identified in the 28% of FN ABs that were classified as inadequate (P <0.01). Conclusions: We concluded that too few FNABs are performed in a fashion tha t permits definitive cytological interpretation. Inadequate FNABs are less likely to detect malignancy. After excluding inadequate preparations, FNABs interpreted as definite cancer and as benign are highly accurate in identi fying patients with and without cancer. (C) 2001 Excerpta Medica, Inc. All rights reserved.