The prevalence of the axillo-inguinal lymphatic pathway in lymphedema of the extremities and potential therapeutic implications

Background: The axillo-inguinal (or inguino-axillary) is a compensatory lymphatic drainage pathway regularly utilized by lymphedema therapists when applying manual lymphatic drainage (MLD) for upper and lower extremity lymphedema. However, there is limited evidence of the frequency of this pathway and the characteristics of patients with lymphedema in which this pathway is present. Indocyanine green (ICG) lymphography is an imaging technique that has the capability to identify lymphatic drainage pathways in lymphedema when combined with MLD. In this study, we used ICG lymphography in patients with upper and lower extremity lymphedema to investigate the presence of this pathway and its clinical characteristics. Methods and Results: A retrospective cohort audit of 563 patients with lymphedema (285 with upper extremity and 278 with lower extremity) who underwent ICG lymphography was conducted in combination with MLD. Compensatory lymphatic drainage was investigated. Patients demonstrating the axillo-inguinal pathway were identified, and their clinical characteristics were recorded. The axillo-inguinal pathway was not demonstrated in any patient with upper extremity and only five patients with lower extremity lymphedema. Of these five patients, all were female with a history of secondary cancer-related lymphedema following gynecological cancer. The majority (four) had bilateral lymphedema extending to the lower abdomen and presented with a greater severity of lymphedema. Conclusions: These findings suggest that the axillo-inguinal pathway is an infrequent compensatory drainage pathway in lower extremity lymphedema and rare in upper extremity lymphedema. Our findings have clinical implications for lymphedema management, in particular, the sequence in which MLD is applied.