How would you manage a pT2N1a invasive ductal carcinoma s/p lumpectomy and sentinel lymph node biopsy with ECE, and two mildly avid axillary lymph nodes on post-op PET/CT?

We often see mildly active lymph nodes on post-op PET/CT scans, so one important initial question is how long after the surgery the PET/CT was performed. Another question would be how many total lymph nodes were removed at the sentinel biopsy. If the scan was done ~6 weeks post-op and the patient had a few other negative sentinel lymph nodes, then mildly avid axillary lymph nodes on the PET/CT most likely are reactive. Since ECE was not specifically examined on either Z11 or AMAROS, I would cover the ipsilateral whole breast and elective regional lymph nodes (levels 1-3, IMN and SCV) with a breast cavity boost in either a conventional or moderately hypofractionated regimen, depending on patient preference and body habitus. I do not think th...

If the patient did not have a pre-op diagnostic CT or MRI, one thing that can be helpful is to look at the lymphoscintigraphy images if your institution obtains a CT. This can be particularly helpful if you see a suspicious IMN post-op on your sim and/or diagnostic imaging and didn't have a contrast-enhanced CT or MRI prior to surgery. If the IMN looked enlarged even on the lymphoscintigraphy CT, which is pre-op by definition, it makes me favor treating it as involved, since any post-op imaging is now confounded by post-op inflammation. This approach can also be useful for axillary nodes. As mentioned, there should have been a pre-op axillary ultrasound, but if the nodes are deep and wouldn't have been easily evaluated by ultrasound and you...

Did the patient have a pre-surgery axillary sonogram? This is most likely reactive, but to confirm, I would favor a repeat axillary ultrasound and biopsy if it looks abnormal, as management will change if the patient has residual gross disease.