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

PURPOSE: To analyze the malignant breast neoplasms missed as tumor on ultrasonography (US).

MATERIAL AND METHODS: A total of 355 malignant tumors were confirmed at histology among 2,985 consecutive patients who underwent breast US. There were no prospectively recorded mammographic findings in 28 of the 355 tumors. The remaining 327 tumors included 16 ductal carcinomas in situ (DCIS) and 66 invasive carcinomas with suspicious microcalcifications on mammography. Excluding these 82 tumors because US would not have been indicated using strict criteria, a subpopulation of 245 noncalcified invasive malignant tumors remained for analysis. The neoplasms missed as tumor on US were analyzed for 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 1 12 nonpalpable malignancies. Most of the missed tumors were DCIS and microinvasive ductal 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 malignancies, 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 mammography, by far the most malignant breast neoplasms are diagnosed as a tumor on US.