Objectives: To evaluate the accuracy of using radiologic, cytologic and integrated radiologic and cytologic criteria in diagnosis of nonpalpable breast lesions.
Material and Method: From January 2003 to May 2004, a prospective study of performing fine-needle aspiration biopsy (FNAB) was carried out at King Chulalongkorn Memorial Hospital on female patients with nonpalpable or vaguely palpable lumps that needed ultrasound localization for the direction and depth.
Results: There were 162 lesions from 150 patients, consisting of 29 malignant neoplasms (17.9%) and 133 benign lesions (82.1%). Of the 107 classified as subcentimeter focal lesions (< 1 x 1 cm2 in size), two of radiological malignancy were false and two others were falsely negative by cytology. While the 23 large/illdefined lesions (> 1.5 x 1.5 cm2 in size), one hiding malignant lesion adjacent to a prominent intraduct papilloma was missed. Two others had falsely negative cytologic diagnosis. The integrated criteria achieved accuracy and sensitivity of 97.5% and 93% compared with the cytology, 96.3% and 82.8% and the better scenario of radiology, 95.7% and 82.8% respectively.
Conclusion: The integrated criteria provide the most accuracy rate and sensitivity rate for detection of malignancy in nonpalpable breast lesions.

Keywords: FNA, Cytology, Breast, Imaging, Nonpalpable, Impalpable