Usefulness of mammoty in diagnosis and therapy of nonpalpable lesions

PURPOSE: to evaluate the accuracy of directional vacuum-assisted biopsy (mammotomy), guided by ultrasonography, in the diagnosis of nonpalpable breast lesion, as compared with excision biopsy, and to evaluate the therapeutic value of mammotomy in nonpalpable benign lesions. METHODS: 114 patients, who presented nonpalpable breast lesion, visible on ultrasonography, were included. The patients were referred to complementary ultrasonographic evaluation due to mastalgia or earlier found mammographic alteration. All were submitted to mammotomy guided by ultrasonography using Mammotome® (Biopsys, Irvine, Califórnia), with a 11 gauge needle. The excision biopsy was performed with previous puncture of those patients who presented residual lesion after the mammotomy, that is, 88 patients. To evaluate comparatively the mammotomy results with those of excision biopsy, the sensitivity and specificity rates, positive and negative predictive values, and the agreement proportion were calculated. Not only the sensibilities, but also the specificities and the agreement proportions of both examinations were compared through Wald statistics, using a model for classified data. RESULTS: of 114 patients, 88 were submitted to excision biopsy. The remaining 26 did not show post-mammotomy lesions visible on ultrasonography, and for one year they were without alterations on the bi-annual mammographic and ultrasonographic examinations. The diameter of those lesions was less than 1.5 cm. Among the 88 patients that underwent excision biopsy, 69 (78,4%) showed benign and 19 (21,6%), malignant lesions. Mammotomy diagnosed 16 of the malignant lesions, with three false-negative and no false-positive results. The false results occurred in the first cases, showing the existence of a learning curve of the method, or due to technical difficulty such as the blurring of ultrasonographic image by bleeding. The sensitivity and specificity were 84,2% and 100%, respectively, with 100% positive predictive and 95,8% predictive negative values. The mammotomy accuracy was 96,6%. Complications were rare: two cases of hematomas, none of them needing surgical drainage; a case of vasovagal reflex not allowing the conclusion of the examination. The cosmetic results were very favorable due to small incisions (3 mm) and to the smaller amount of excised tissue. CONCLUSION: mammotomy guided by ultrasonography showed to be a diagnostic method with high accuracy, and it may be used as therapy for benign, smaller than 1.5 cm lesions.

Mammotomy; Nonpalpable breast lesions; Breast cancer

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