Correlation between ultrasound characteristics, mammographic findings and histological grade in patients with invasive ductal carcinoma of the breast.

AIM

To investigate the relationship between ultrasound characteristics, mammographic findings and histological grade in cases of invasive ductal carcinoma which produce a mass on ultrasound.

MATERIAL AND METHODS

A retrospective review was performed of the imaging findings in 120 patients diagnosed with invasive ductal carcinoma of the breast between January 1996 and December 1997. Imaging findings were correlated with the histological grade of tumour.

RESULTS

High-grade tumours were significantly larger both on ultrasound and mammography (P < 0.016). A spiculated margin on mammogram was documented in 72% of low-grade tumours compared with only 24% of high-grade tumours (P = 0.001). Twenty-two per cent of low-grade tumours had a poorly defined margin on mammography compared with 66% of high-grade tumours (P = 0.001). At ultrasound, 16% of high-grade tumours (95% confidence limits 7-29%) had a well-defined margin. Acoustic enhancement was seen in 36% of high-grade tumours compared with only 9% of low and intermediate-grade tumours (P = 0.003): 22% of all tumours showed acoustic enhancement. Acoustic shadowing was seen in 71% of low-grade tumours compared with only 28% of high-grade tumours (P = 0.003). Malignant-type microcalcification was seen on mammogram in 6% of low-grade tumours compared with 31% of high-grade tumours (P = 0.045).

CONCLUSION

The classical appearance of a malignant breast mass as a spiculated mass on mammogram associated with acoustic shadowing on ultrasound is more typical of a low-grade tumour. In comparison, high-grade tumours are more likely to demonstrate posterior acoustic enhancement, and a proportion has a well-defined margin on ultrasound. Therefore, high-grade invasive ductal carcinoma may paradoxically display similar imaging features to a benign breast mass.