Pathological changes in the lymphatic system of patients with secondary upper limb lymphoedema

Taro Mikami1, Asumi Koyama2, Koukichi Hashimoto1, Jiro Maegawa3, Yuichiro Yabuki1, Shintaro Kagimoto1, Shinya Kitayama1, Tomohiro Kaneta4, Kazunori Yasumura5, Shinobu Matsubara6 & Toshinori Iwai7. Scientific Reports (2019) 9:8499

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Main findings

  • On the basis of the findings of clinical examination, all 98 limbs on the non-affected side were classified as type I Dermal Back Flow (DBF), which demonstrated that, in general, no lymph stasis occurred in the upper limb without clinical symptoms of lymphoedema. Lymph nodes around the clavicle were found in almost all of the non-affected sides and there were no deep pathway-dominant types in cases with non-affected limbs. This finding implies that superficial pathways comprise the dominant lymph flow to the lymph nodes around the clavicle.
  • As the DBF appeared at the more distal part of the upper limb, the number of lymph nodes around the clavicle appeared to decrease.
  • Deep pathways may be more dominant pathways in severe cases, in which the DBF appears in the distal portions.
  • The lymph flow of the upper limb to the lymph nodes in the ipsilateral axilla is thought to be deep pathway-dominant, considering the fact that all except three cases had undergone axillary dissection. We may build a hypothesis as follows. First, the deep lymph flow pathways are affected soon after axillary dissection, following which the superficial pathways become dominant and the lymph flows to the lymph nodes around the clavicle.
  • Second, when these alternative pathways are overloaded, the lymphoedema progresses along with histological changes in the lymphatic vessels and the surrounding tissue in the superficial layer (i.e. the superficial lymphatics become disordered). At the same time, the deep pathways, which are surrounded by muscle that rarely undergoes fibrosis, become dominant.
  • As the severity of lymphoedema worsens, the lymph flow in the deep layer becomes dominant, and the flow into the lymph nodes around the clavicle decrease.