[Diagnostic framework of nonpalpable lesions of the breast]

Mammography is the most sensitive test for non-palpable lesions, but its specificity is quite limited. When a decision for biopsy is based only on the mammographic appearance the benign/malignant biopsy ratio (B/M) is around 3:1. The B/M varies according to the radiological pattern being favourable for stellate opacities, high for regular opacities, and intermediate for distortions and microcalcifications. Aspiration cytology of non-palpable lesions, either sonographically or stereotaxically guided, is highly accurate. When the decision for surgical biopsy is taken also on the basis of cytology, B/M may be reduced by up to 0.5:1. As false negatives are expected for cytology, lesions which are strongly suspicious at mammography must be biopsied anyway. Sonography guided aspiration is possible in about a half of mammographically detected non-palpable lesions, particularly for opacities, whereas distortions and microcalcification are seldom visualized at sonography. Cytology should be routinely performed in the presence of questionable non-palpable lesions.