Invasive lobular carcinoma: sonographic features of cancers detected in a BreastScreen Program.

Sixty-two screen-detected invasive lobular carcinomas (ILC) were studied for sonographic, mammographic, clinical and histological findings. Ultrasound (US) features were compared with 60 invasive duct cancers (IDC). Size and axillary lymph node status in ILC were compared with all other cancers detected. In 41 ILC examined with US, 36 were found as masses (87.8% sensitivity; 95% CI 77.8-97.8%). Some US features of ILC and IDC differed: ILC were 9.94 times more likely to be hyperechoic (odds ratio, OR, 9.94; 95% CI 3.28-31.74) and 77% less likely to be taller than wide (OR 0.23; 95% CI 0.18-0.62). Thirty-three ILC showed typical malignant features of spiculate margins and acoustic shadowing. invasive lobular carcinomas had a greater mean diameter (20.4 mm; n = 60) than other invasive cancers (14.4 mm; n = 322) (P < 0.001). Ultrasound-guided needle biopsy was the method of diagnosis in 26 of 41 impalpable ILC (63%). Ultrasound has high sensitivity in characterizing screen-detected ILC, which may have atypical sonographic features including hyperechogenicity and a wider than tall shape. Ultrasound was an important contributor to diagnosis.