Internal mammary lymph node biopsy during delayed free flap breast reconstruction: case series and review of the literature

Background: Internal mammary vessels are often used as recipient vessels during free flap breast reconstruction, especially in delayed reconstruction. Vessel dissection occasionally results in incidental identification of internal mammary lymph nodes (IMLNs). Some studies have reported the positivity of these nodes but few studies have focused on delayed reconstruction and no other study examined the difference between patients with and without artificial materials. Methods: This is a retrospective review of patients undergoing delayed free flap breast reconstruction using internal mammary vessels. If IMLNs were accidentally identified during preparation of recipient vessels, the authors sent it for pathological review. Patient characteristics, tumor staging, IMLN positivity, treatment alteration after operation, and outcome were studied. Results: Overall, 174 patients underwent delayed free flap breast reconstruction; internal mammary vessels were exposed in 167 patients. Of these, 68 IMLNs (65 patients, 38.9%) were identified and sampled. IMLNs were identified in 40 patients (43.0%) in patients with artificial materials such as tissue expander, silicone implant, and injected foreign material for breast augmentation, while in 25 patients (33.8%) without them. Three patients (4.6%) were tumor positive. One patient was found to have multiple metastasis and two of three patients had an increase in cancer stage after reconstruction. Two patients had changes in cancer treatment after reconstruction. All patients with positive IMLNs were alive at the last follow-up. Conclusions: During delayed free flap breast reconstruction, IMLNs are identified more frequently in patients with artificial materials than patients without them. Its positivity is rare, but it might affect breast cancer reevaluation and treatment after reconstruction. Level of evidence: Level IV, diagnostic study.