Ultrasonography of malignant breast neoplasms - Analysis of carcinomas missed as tumor

Purpose: To analyze the malignant breast neoplasms missed as tumor on ultra sonography (US). Material and Methods: A total of 355 malignant tumors were confirmed at his tology among 2,985 consecutive patients who underwent breast US. There were no prospectively recorded mammographic findings in 28 of the 355 tumors. T he remaining 327 tumors included 16 ductal carcinomas in situ (DCIS) and 66 invasive carcinomas with suspicious microcalcifications on mammography. Ex cluding these 82 tumors because US would not have been indicated using stri ct criteria, a subpopulation of 245 noncalcified invasive malignant tumors remained for analysis. The neoplasms missed as tumor on US were analyzed fo r the whole tumor group (n=355) and the subpopulation (n=245). Results: 42 (11.8%) of the 355 malignant neoplasms were missed as tumor on US, including 6 (2.5%) of the 243 palpable and 36 (32.1%) of the 112 nonpal pable malignancies. Most of the missed tumors were DCIS and microinvasive d uctal carcinomas dominated by DCIS. In the subpopulation, 14 (5.7%) of the 245 malignancies were missed as tumor on US, including 4 (2.2%) of the 180 palpable and 10 (15.4%) of the 65 nonpalpable lesions. Of the 245 malignanc ies, 6 (2.4%) had a normal US finding, including 2 palpable retropapillary tumors and 4 incidental findings at histology. Conclusion: Using strict criteria for performing US as an adjunct to mammog raphy, by far the most malignant breast neoplasms are diagnosed as a tumor on US.