Superior Extent of Modified Radical Mastectomy
The internal landmark defining the superior extent of a Modified Radical Mastectomy (MRM) is the axillary vein. 1
Anatomical Boundary Definition
The axillary vein serves as the primary superior landmark that must be clearly exposed during the procedure. 1 This boundary is critical because:
- Dissection should remain inferior to the axillary vein, encompassing level I and II lymph nodes from the latissimus dorsi muscle laterally to the medial border of the pectoralis minor muscle. 1
- The axillary vein represents the anatomical ceiling of the dissection field and should not be crossed. 1
Critical Structures at the Superior Boundary
When operating near the axillary vein, several neurovascular structures require preservation:
- The long thoracic nerve must be identified and preserved to prevent winged scapula deformity. 1
- The thoracodorsal nerve and vessels should be maintained to preserve function. 1
- These structures run in close proximity to the axillary vein and are at risk during superior dissection. 1
Technical Considerations
Circumferential stripping of the axillary vein is contraindicated, as this technique provides no staging benefit and significantly increases the risk of lymphedema. 1 The dissection should expose the inferior surface of the axillary vein without aggressive manipulation of the vessel itself.
Common Pitfalls to Avoid
- Never extend dissection superior to the axillary vein. 1 This provides no additional staging information and substantially increases morbidity including nerve injury and lymphedema risk.
- Avoid routine level III dissection (superior to the pectoralis minor muscle) in the absence of gross disease, as this increases complications without survival benefit. 1
- Do not perform circumferential dissection around the axillary vein, which unnecessarily elevates lymphedema risk. 1
Standard Lymph Node Dissection Requirements
For adequate staging in MRM, level I and II axillary lymph node dissection requires removal of at least 10 lymph nodes, with the superior boundary consistently defined by the axillary vein. 1