Classification of superficial lymphatic pathways in the upper extremity and incidence of lymphatic obstruction according to the lymphatic pathways in patients with unilateral upper extremity lymphedema

Background: Indocyanine green (ICG) lymphography is frequently used in the diagnosis of lymphedema, as well as the planning of its surgical management, but the typical anatomy of the superficial lymphatic pathways is incompletely delineated. This study aims to evaluate the topographical anatomy of superficial lymphatic vessels of the upper extremity Methods: Sixty consecutive patients undergoing lymphaticovenular anastomosis for unilateral upper extremity lymphedema were selected. Lymphatic mapping was performed on the normal contralateral arm with ICG lymphography. A single upper arm reference line and two separate forearm reference lines (anterior and posterior) were drawn between anatomic landmarks. Lymphatic pathways were analyzed based on distances (cm) from the reference lines and were compared with those in lymphedema arms. Results: Mean age of the patients were 54.6 ± 8.4 years. Three lymphatic flow pathways were identified: anterior (100%), posterior (96.6%), and posterior-ulnar lymphatic (33.3%) vessels. The anterior and posterior lymphatic vessels ran along the anterior and posterior reference lines, respectively, on the forearm (within 2 cm) and medial to the upper arm reference line. In arms with lymphedema, the absence of lymphatic flow was most commonly observed in posterior lymphatics (29/59, 49%), followed by anterior (15/60, 25%) and posterior-ulnar lymphatics (1/20, 5%). Compared to normal arms, new lymphatic flow through posterior-ulnar lymphatics was observed in 34.5% of patients (10/29) in whom posterior lymphatics was completely obstructed. Conclusions: Superficial lymphatic vessels can be classified into anterior, posterior, and posterior-ulnar lymphatic vessels. Posterior-ulnar lymphatic vessels might be least affected by lymphosclerosis in patients with lymphedema.