title: Analysis of false results in a series of 835 fine needle aspirates of breast lesions.
abstract: OBJECTIVE
  To analyze cases of false diagnoses from a large series to help increase the accuracy of fine needle aspiration of palpable breast lesions.
  
  
  METHODS
  The results of FNA of 835 palpable breast lesions were analyzed to determine the reasons for false positive, false negative and false suspicious diagnoses.
  
  
  RESULTS
  Of the 835 aspirates, 174 were reported as positive, 549 as negative and 66 as suspicious or atypical but not diagnostic of malignancy. Forty-six cases were considered unsatisfactory. Tissue was available for comparison in 286 cases. The cytologic diagnoses in these cases were reported as follows: positive, 125 (43.7%); suspicious, 33 (11.5%); atypical, 18 (6.2%); negative, 92 (32%); and unsatisfactory, 18 (6.2%). There was one false positive diagnosis, yielding a false positive rate of 0.8%. This lesion was a case of fibrocystic change with hyperplasia, focal fat necrosis and reparative atypia. There were 14 false negative cases, resulting in a false negative rate of 13.2%. Nearly all these cases were sampling errors and included infiltrating ductal carcinomas (9), ductal carcinomas in situ (2), infiltrating lobular carcinomas (2) and tubular carcinoma (1). Most of the suspicious and atypical lesions proved to be carcinomas (35/50). The remainder were fibroadenomas (6), fibrocystic change (4), gynecomastia (2), adenosis (2) and granulomatous mastitis (1).
  
  
  CONCLUSIONS
  A positive diagnosis of malignancy by FNA is reliable in establishing the diagnosis and planning the treatment of breast cancer. The false-positive rate is very low, with only a single case reported in 835 aspirates. Most false negatives are due to sampling and not to interpretive difficulties. The category "suspicious but not diagnostic of malignancy" serves a useful purpose in management of patients with breast lumps.
authors.affiliation: Department of Pathology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Willis
authors.forename: I
authors.initials: I
authors.lastname: Ramzy
mesh_terms: D001707:Biopsy, Needle; D001943:Breast Neoplasms / Q000473:pathology*; D003951:Diagnostic Errors; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans