The positive predictive value of mammographic signs: a review of 425 non-palpable breast lesions.

The sensitivity of mammography in cancer detection needs to be high but is also important to achieve a high diagnostic specificity to avoid the morbidity associated with unnecessary surgical biopsy. We have reviewed the mammographic features of non-palpable breast lesions to identify factors which may improve the specificity of mammographic interpretation and reduce the number of open surgical biopsies for benign lesions. Four hundred and twenty-five surgical biopsies of non-palpable breast lesions were performed following image-guided localization between January 1987 and April 1994. The mammographic features of these lesions were reviewed and correlated with their histology. Two hundred and twenty-five of the excised lesions were malignant and 200 were benign giving a benign to malignant ratio of 0.88:1 and a positive predictive value (PPV) for malignancy of 53%. Pre-operative fine needle aspiration cytology was performed in 359 cases (84%). The PPV for the various mammographic abnormalities following the assessment process ranged from 4% for well defined masses to 94% for spiculate masses. The PPV for all microcalcifications was 45%. For impalpable lesions it is our policy to recommend surgical excision of all spiculate masses, parenchymal deformities and high risk microcalcifications. Ill defined masses are managed according to fine needle aspiration cytology (FNAC) and/or core biopsy results. Masses which are entirely well-defined are regarded as benign and are not recalled for assessment unless they are new or enlarging. Needle core biopsy has been added to our preoperative assessment of mammographically indeterminate microcalcifications with the aim of reducing the number of benign surgical biopsies.