Ultrasound findings and histological features of ductal carcinoma in situ detected by ultrasound examination alone

With the increasing use of high-resolution ultrasound (US) examination, many breast carcinomas that cannot be identified by mammography (MMG) alone have been detected. Many of these carcinomas are ductal carcinoma in situ (DCIS) and small-sized invasive carcinomas. Until date, DCISs have often been described as palpable masses with calcifications on MMG, but what are the characteristics of DCISs that are detectable by US alone?

One hundred fifty cases with DCIS that we experienced at our clinic from 2003 to 2007 were classified into 47 cases (echo group) diagnosed by US alone and 103 cases (MMG/PE group) diagnosed by MMG or clinically.

US findings of the echo group showed cystic or solid lesions in 37 cases (79%). The mean age of the echo group was significantly higher than that of the MMG/PE group (59.6 vs. 51.2 years; P < 0.01). Tumor sizes detected by US were 5.7 + 2.8 and 11.5 + 10.8 mm (P < 0.001), respectively. The tumor sizes of the echo group were, therefore, approximately half that of the MMG/PE group. Extensive intraductal components were significantly fewer in the echo group, and tumor grades of the echo group were significantly low (Van Nuys classification). In the echo group, all cases with a tumor size <5 mm were grade 1 by Van Nuys classification. In addition, cases with ≥5 mm tumor size had a significantly lower tumor grade in the echo group than in the MMG/PE group.

Cystic or solid lesions accounted for approximately 80% of US findings of DCISs detected by US alone, and most were similar to benign forms. Moreover, most DCISs detected by US alone were localized and of low grade (Van Nuys classification).