Staging primary breast cancer. Are there tumour pathological features that correlate with a false-negative axillary ultrasound?

To investigate whether the histopathological characteristics of primary breast cancer tumours could predict the likelihood of false-negative axillary ultrasound.Screening and symptomatic patients were identified from pathology records and imaging and pathology records reviewed. True and false-negative axillary staging ultrasound groups were compared statistically in terms of tumour size, pathological type and grade, lymphovascular invasion, and oestrogen receptor (ER) status.Of 155 women with normal ultrasounds, 45 (29%) were node positive at axillary surgery. Breast tumour size was significantly different with the average size smaller in the true-negative group: 21 versus 30 mm (p < 0.02). The histological type varied significantly between the groups, with more lobular carcinomas in the false-negative group [6/110 (5%) versus 6/45 (13%), p < 0.001]. The false-negative group was also more likely to show lymphovascular invasion in the breast [6/110 (5%) versus 14/45 (31%), p < 0.001]. There was no significant difference in tumour grade or ER status.The present study has found significant differences in tumour characteristics between women with true-negative and false-negative axillary staging ultrasound in terms of size, primary tumour histological type and presence of lymphovascular invasion. In particular, axillary ultrasound in primary lobular carcinoma may be less accurate and a negative result is more likely to be spurious than with primary ductal carcinomas.