RÉSUMÉ
OBJECTIVE: To examine the biopsy rate and positive predictive value (PPV) for breast cancer in lesions categorized as BI-RADS (Breast Imaging reporting and Data System) category 4. MATERIAL AND METHOD: The medical records of patients with BIRADS 4 breast lesion diagnosed at the breast diagnostic center Ramathibodi Hospital between December 1, 2004 and December 31, 2005 were retrospectively reviewed. PPV was calculated for patients who had biopsy performed or had clinical follow-up for at least two years. The radiographic and pathological findings were compared. RESULTS: The biopsy rate of 536 lesions categorized as BI-RADS 4 was 75% (403 of 536). Malignancy was found in 95 of 460 patients; or a PPV of 21%, PPVs for subcategories 4A, 4B and 4C, were 9%, 21% and 57%, respectively. The most common malignancy was invasive ductal carcinoma (67%). Patients with advanced age, having a clinically palpable breast mass of large size, with mammographic findings of architectural distortion and asymmetrical density were significantly associated with a higher risk of breast cancer. CONCLUSION: PPV for malignancy in the present study was comparable to previous studies. In subcategories 4B and 4C, the malignancy rate was higher than that in subcategory 4A.