The surgical and oncologic significance of the axillary arch during axillary lymphadenectomy.

An uncommon and often-overlooked anatomic variation of the latissimus dorsi muscle is the axillary arch. It is formed by an anomalous slip of the muscle that arises from the body of the latissimus dorsi but then inserts along with the pectoralis major muscle anterior to the axillary vein and neurovascular bundle. If an axillary arch is encountered during axillary lymphadenectomy, the lymph nodes posterior and lateral to the arch should be excised. Experience with a number of cases is used to consider local therapeutic and staging factors.