What are the anatomical borders of a mastectomy?

From the Guidelines

The anatomical borders of a mastectomy typically include the clavicle superiorly, the sternum medially, the latissimus dorsi muscle laterally, and the rectus abdominis fascia or inframammary fold inferiorly. These borders define the surgical field where breast tissue is removed during the procedure. The skin incision generally extends from the sternum to the anterior axillary line and encompasses the nipple-areolar complex. In a modified radical mastectomy, the pectoralis major muscle is preserved while the pectoralis minor muscle may be either preserved or removed to facilitate axillary lymph node dissection. The axillary contents, including lymph nodes, are typically removed up to the axillary vein superiorly. These anatomical borders ensure complete removal of breast tissue while preserving vital structures such as major blood vessels, nerves, and muscles not involved by the disease process. The precise borders may vary slightly based on the specific type of mastectomy being performed (simple, modified radical, or radical) and the patient's individual anatomy. According to the most recent guidelines 1, skin-sparing mastectomy procedures are appropriate for some patients and involve removal of the breast parenchyma, including the NAC, while preserving most of the original skin envelope.

Key Considerations

• The anatomical borders of a mastectomy are crucial in ensuring complete removal of breast tissue while preserving vital structures.
• The type of mastectomy being performed (simple, modified radical, or radical) and the patient's individual anatomy may influence the precise borders.
• Skin-sparing mastectomy procedures, as described in the guidelines 1, offer advantages such as improved cosmetic outcome and the ability to perform immediate reconstruction.
• The guidelines also emphasize the importance of careful patient selection and assessment of nipple margins when considering NAC-sparing procedures 1.

Surgical Approach

• The skin incision for a mastectomy typically extends from the sternum to the anterior axillary line and encompasses the nipple-areolar complex.
• The axillary contents, including lymph nodes, are removed up to the axillary vein superiorly.
• The pectoralis major muscle is preserved in a modified radical mastectomy, while the pectoralis minor muscle may be either preserved or removed to facilitate axillary lymph node dissection. As noted in the guidelines 1, the use of NAC-sparing procedures may be an option in patients who are carefully selected by experienced multidisciplinary teams.

Patient Selection

• Patients with early-stage, biologically favorable invasive cancers or DCIS that is peripherally located in the breast (>2 cm from nipple) may be suitable for NAC-sparing procedures, as indicated in the guidelines 1.
• Contraindications for nipple preservation include evidence of nipple involvement, such as Paget’s disease or other nipple discharge associated with malignancy, and/or imaging findings suggesting malignant involvement of nipple and subareolar tissues. The guidelines 1 emphasize the importance of careful patient selection and assessment of nipple margins when considering NAC-sparing procedures.

From the Research

Anatomical Borders of Mastectomy

The anatomical borders of a mastectomy are not explicitly defined in the provided studies. However, the studies discuss the different types of mastectomies, including nipple-sparing mastectomy (NSM), skin-sparing mastectomy (SSM), and modified radical mastectomy (MRM).

• The studies suggest that the anatomical borders of a mastectomy may vary depending on the type of mastectomy performed 2, 3, 4, 5, 6.
• NSM is a surgical protocol that preserves the nipple-areola complex, while SSM preserves the skin envelope 2, 3, 4.
• MRM is a more traditional type of mastectomy that removes the breast tissue, nipple-areola complex, and skin envelope 3, 5.
• The studies do not provide a clear definition of the anatomical borders of a mastectomy, but they suggest that the borders may be influenced by the type of mastectomy performed and the individual patient's anatomy 2, 3, 4, 5, 6.

Key Findings

• The studies suggest that NSM and SSM may be associated with better cosmetic outcomes and quality of life compared to MRM 3, 4, 5, 6.
• The anatomical borders of a mastectomy may be influenced by the surgical technique used and the individual patient's anatomy 2, 3, 4, 5, 6.
• The studies do not provide a clear definition of the anatomical borders of a mastectomy, but they suggest that the borders may vary depending on the type of mastectomy performed and the individual patient's anatomy 2, 3, 4, 5, 6.