Axillary scanning in women undergoing a diagnostic breast ultrasound has minimal impact on cancer detection, according to findings published April 6 in Clinical Imaging.
A team led by Dr. Iris Chen from the University of California, Los Angeles found that less than 1% of incidental axillary findings were given a BI-RADS category 3 or 4, none of which resulted in the diagnosis of an occult breast cancer. In other words, such scanning of the axilla may not be needed.
"Omitting routine scanning of the axilla for all diagnostic breast ultrasounds may save time and reduce patient anxiety related to unnecessary follow-up and biopsies, without adversely affecting patient care," Chen and co-authors wrote.
Breast ultrasound is used in women undergoing diagnostic and screening breast imaging. However, the researchers noted that it can have high false-positive rates and can be time-consuming to perform.
While scanning the axilla is good for assessing axillary lymphadenopathy, it may be merely optional in women with a low likelihood of breast cancer. One side effect of the COVID-19 vaccine and booster is the presence of axillary lymphadenopathy, most cases of which resolve on their own.
Chen and colleagues wanted to look at the clinical impact of incidental axillary findings found on diagnostic breast ultrasound scans in their retrospective study. They did so at a single multisite institution that has a standard protocol for scanning the axilla during all breast ultrasound exams.
The team also reviewed follow-up imaging, relevant clinical history, and pathology results. It also divided positive axillary findings into incidental or nonincidental findings.
Overall, the researchers reviewed 19,695 diagnostic ultrasound exams performed between 2017 and 2019. Of these, 91 (0.5%) had incidental axillary findings that were assigned a BI-RADS category of 3 or 4. None of these results led to an occult breast cancer diagnosis. The team also found that one biopsy-proven small lymphocytic lymphoma/chronic lymphocytic leukemia was diagnosed that was otherwise clinically occult.
The study authors suggested that the low abnormal interpretation rate may be related in part to the experience of radiologists and technologists, along with mildly prominent lymph nodes being classified as benign. They also wrote that their findings indicate that routine scanning of the axilla for all diagnostic breast ultrasound exams can be omitted.
"We have demonstrated that decreasing unnecessary axillary scanning would lead to fewer false positives without missing any occult breast cancers," Chen and colleagues wrote.
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
