Anatomy and physiology of the sentinel lymph nodes of the upper extremity: Implications for axillary reverse mapping in breast cancer

Alternative Lymphatic Drainage Pathways in the Trunk Following Oncologic Therapy

BACKGROUND

Anatomic and functional descriptions of trunk and breast lymphedema following breast cancer treatment are emerging as indicators of lymphatic dysfunction. Indocyanine green-lymphangiography has been instrumental in characterizing this dysfunction in the extremity and can be applied to other regions. Previous work has established a validated Pittsburgh Trunk Lymphedema Staging System to characterize such affected areas. This study aims to identify risk and protective factors for the development of truncal and upper extremity lymphedema using alternative lymphatic drainage, providing implications for medical and surgical treatment.

METHODS

Patients undergoing revisional breast surgery with suspicion of upper extremity lymphedema between 12/2014 and 3/2020 were offered lymphangiography. The breast and lateral/anterior trunks were visualized and blindly evaluated for axillary and inguinal lymphatic flow. A linear-weighted Cohen's kappa statistic was calculated comparing alternative drainage evaluation. Binomial regression was used to compute relative risks (RRs). Significance was assessed at alpha = 0.05.

RESULTS

Eighty-six sides (46 patients) were included. Twelve sides underwent no treatment and were considered controls. Eighty-eight percent of the noncontrols had alternative lymphatic flow to the ipsilateral axillae (64%), ipsilateral groins (57%), contralateral axillae (20.3%), and contralateral groins (9.3%). Cohen's kappa for alternative drainage was 0.631 ± 0.043. Ipsilateral axillary and contralateral inguinal drainage were associated with reduced risk of developing truncal lymphedema [RR 0.78, confidence interval (CI) 0.63-0.97, P = 0.04; RR 0.32, CI 0.13-0.79, P = 0.01, respectively]. Radiation therapy increased risk of truncal and upper extremity lymphedema (RR 3.69, CI 0.96-14.15, P = 0.02; RR 1.92, CI 1.09-3.39, P = 0.03, respectively). Contralateral axillary drainage and axillary lymph node dissection were associated with increased risk of upper extremity lymphedema (RR 4.25, CI 1.09-16.61, P = 0.01; RR 2.83, CI 1.23-6.52, P = 0.01, respectively).

CONCLUSIONS

Building upon previous work, this study shows risk and protective factors for the development of truncal and upper extremity lymphedema. Most prevalent alternative channels drain to the ipsilateral axilla and groin. Ipsilateral axillary and contralateral inguinal drainage were associated with reduced risk of truncal lymphedema. Patients with radiation, axillary dissection, and contralateral axillary drainage were associated with increased risk of upper extremity lymphedema. These findings have important clinical implications for postoperative manual lymphatic drainage and for determining eligibility for lymphovenous bypass surgery.

Magnetic resonance imaging evaluation of single axillary lymph node metastasis in breast cancer: Emphasis on the location of lymph nodes

To evaluate the frequency and location of abnormal lymph nodes (LNs) in breast cancer patients with a single axillary lymph node (ALN) metastasis on breast magnetic resonance imaging (MRI). We retrospectively reviewed the MRI findings of 219 consecutive patients with breast cancer with single ALN metastasis who were surgically confirmed at our institution between January 2018 and December 2018. The morphological features and locations of the abnormal LN on MRI were analyzed. Pathology reports were reviewed to evaluate the size of the metastases and whether they were sentinel LNs (SLNs). Of the 219 patients with a single ALN metastasis, 56 (25.6%) showed abnormal MRI findings. Of these, 54 (96.4%) had either the lowest or second-lowest LN in the level I axilla. In 184 (91.5%) of 201 patients who underwent SLN biopsy, the metastatic LN were SLN. Macrometastases were found more frequently in cases with abnormal LNs than in those with normal-looking LNs (P = .004). The most frequent morphological feature of metastatic ALNs was a diffuse cortical thickening of 3 to 5 mm (37.5%). Although MRI findings of single ALN metastasis in breast cancer patients are none or minimal, abnormalities are observed in the lowest or second-lowest LN in the lower axilla when present, suggesting the location of the SLNs.