Locating the axillary vein and preserving the medial pectoral nerve.

The exposure for an axillary dissection has become more limited as surgical treatment for breast cancer has evolved from a radical mastectomy to a limited axillary dissection. Exposure of the axillary vein is made more difficult by the smaller incisions, by preservation of intercostobrachial nerves, and by the induration resulting from a previous sentinel node biopsy. To assist in the identification of the axillary vein, I describe the course of a visible but small vein adjacent to the medial pectoral nerve. The vein can be easily identified at the lateral edge of the pectoralis major. It, frequently together with the medial pectoral nerve, traverses in a craniomedial direction and leads to either the lateral thoracic vein (near its junction with the axillary vein) or directly to the axillary vein. Dissection of this vessel identifies the axillary vein, preserves the medial pectoral nerve and allows a more complete and safe level II dissection.