Superior Extent of Flap in Modified Radical Mastectomy
The superior extent of the flap in a Modified Radical Mastectomy should extend to the clavicle, as the skin envelope and subcutaneous tissue overlying the breast are elevated while preserving the pectoralis major muscle. 1
Anatomical Boundaries of the MRM Flap
The flap raised during MRM encompasses specific anatomical layers and boundaries:
The flap includes skin and subcutaneous tissue overlying the breast parenchyma, extending superiorly to the clavicle, inferiorly to the inframammary fold, medially to the sternal border, and laterally to the latissimus dorsi muscle. 1
The subcutaneous tissue is preserved in the flap to maintain adequate thickness for healing and potential reconstruction. 1
The pectoralis major muscle is preserved beneath the flap, distinguishing MRM from radical mastectomy. 1, 2
Critical Technical Considerations
Flap Thickness and Oncologic Safety
Adequate flap thickness is essential—overly aggressive flap elevation may leave residual breast tissue, increasing local recurrence risk. 1
The flap must be thin enough to remove all breast parenchyma but thick enough to maintain viability, particularly when postoperative radiation therapy is planned. 1
Variations Based on Reconstruction Plans
In skin-sparing mastectomy (a variant of MRM), most of the original skin envelope is preserved for immediate reconstruction, removing only the nipple-areolar complex and previous biopsy sites. 1
The preserved skin flaps provide the foundation for both implant-based and autologous tissue reconstruction. 1
Standard MRM removes the nipple-areolar complex along with all breast tissue, while maintaining the skin envelope boundaries described above. 1
Common Pitfalls to Avoid
Inadequate superior dissection may leave breast tissue near the clavicle, compromising oncologic outcomes. 1
Excessive thinning of the superior flap can lead to skin necrosis, particularly in the subclavicular region where blood supply may be tenuous. 1
Seroma formation is the most common complication in the space beneath the flap and should be anticipated with appropriate drain placement. 1
In inflammatory breast cancer, skin-sparing approaches are contraindicated due to dermal lymphatic involvement—standard flap elevation with skin removal is mandatory. 1
Muscle Preservation Considerations
The pectoralis minor muscle can be preserved (Madden technique) or resected (Patey technique) without affecting surgical outcomes, lymph node yield, or complication rates. 3
Preservation of the lateral pectoralis nerve, which innervates the lower third of the pectoralis major muscle, is recommended to maintain cosmetic results and shoulder function. 4
Incision of the lower lateral fibers of the pectoralis major and detachment of pectoralis minor origins enables excellent axillary exposure while minimizing neurovascular injury. 2