Skin-Sparing Mastectomy (SSM) with DIEP Flap Reconstruction

Overview

Part 1: Skin-Sparing Mastectomy

Definition and Scope

• All glandular breast tissue
• The nipple-areolar complex (NAC)
• Any scars from prior biopsy procedures

• Schwartz's Principles of Surgery, 11e - "A skin-sparing mastectomy removes all breast tissue, the nipple-areola complex, and scars from any prior biopsy procedures. There is a recurrence rate of less than 6% to 8%, comparable to the long-term recurrence rates reported with standard mastectomy, when skin-sparing mastectomy is used for patients with Tis to T3 cancers."

Incision Planning

• An elliptical incision incorporates the NAC and any prior biopsy scar
• Incision planning with the plastic surgeon performing immediate reconstruction is ideal
• This skin envelope is left in place to be filled with autologous tissue

SSM vs. Nipple-Sparing Mastectomy (NSM)

Oncologic Safety

Complications of Mastectomy

• Hematoma (~3%)
• Seroma
• Wound infection
• Skin flap necrosis (higher risk with NSM)
• Chronic pain / phantom breast syndrome
• Arm morbidity (if axillary dissection performed)

Part 2: DIEP Flap Reconstruction

What Is a DIEP Flap?

"The Deep Inferior Epigastric Artery Perforator (DIEP) flap... employs the same flap design as the TRAM flap, but rather than harvesting the entire rectus muscle... only the main one to three perforating vessels are identified during the dissection and preserved with the flap." - Current Surgical Therapy, 14e

Vascular Anatomy

• The deep inferior epigastric artery (DIEA) is a branch of the external iliac artery
• It runs on the deep surface of the rectus abdominis and sends perforators through the muscle and anterior fascia to supply the lower abdominal skin and fat
• In DIEP: only 1-3 dominant perforators are dissected through the muscle, preserving muscle function and fascial integrity

DIEP vs. TRAM Flap

Surgical Technique

1. Flap design - A transverse ellipse is marked on the lower abdomen from hip to hip, just above the mons to just above the umbilicus (similar to an abdominoplasty/tummy tuck design)
2. Perforator identification - Preoperative CT angiography is used to map dominant perforators
3. Dissection - The anterior rectus sheath is incised vertically around the 1-3 chosen perforators; the rectus muscle fibers are split (not divided en masse) to trace perforators back to the DIEA
4. Pedicle harvest - The DIEA and its paired venae comitantes are ligated at their origin from the external iliac
5. Free tissue transfer - The flap is transferred to the chest and the DIEA is microsurgically anastomosed to the internal mammary or thoracodorsal vessels
6. Flap inset - The abdominal tissue is shaped and inset into the preserved skin envelope from the SSM
7. Abdominal closure - The donor site is closed primarily, with fascial re-approximation, usually resulting in an improved abdominal contour

Why DIEP Is the Gold Standard

• Single-stage reconstruction (no expander needed)
• Autologous tissue feels and behaves like natural breast - gains and loses weight with the patient
• Higher long-term satisfaction and psychosocial/sexual well-being vs. implants
• Minimal abdominal wall morbidity compared to TRAM
• No implant = no risk of capsular contracture, BIA-ALCL, or implant failure
• "DIEP flaps have become the gold standard for autologous breast reconstruction." - Current Surgical Therapy, 14e

Recipient Vessels

• Internal mammary artery/vein (IMA/IMV) - Most common; accessed by removing a short segment of rib cartilage (3rd or 4th); provides excellent caliber match
• Thoracodorsal vessels - Alternative; in the axilla

Part 3: Patient Selection

Ideal Candidates for SSM + DIEP

• Breast cancer (Tis to T3) requiring mastectomy, planning immediate reconstruction
• Adequate lower abdominal tissue (BMI consideration - very thin patients may lack sufficient volume)
• No prior abdominoplasty or abdominal free flap (would destroy perforators)
• No active smoking (increases risk of flap loss and mastectomy skin necrosis)
• BMI < 40 kg/m² ideally
• No uncontrolled diabetes (risk of wound dehiscence triples with HbA1c > 6.5%)

Relative Contraindications to DIEP

• Prior abdominal surgery (laparotomy, abdominoplasty) that may have damaged perforators - requires CTA mapping to assess feasibility
• Patients too thin for adequate volume
• Morbid obesity (significantly increases donor site and flap complications)
• Multiple prior abdominal surgeries

Part 4: Role of Radiation Therapy

• Radiation + implants = poor outcomes: Postmastectomy radiation (PMRT) after implant reconstruction raises reconstructive failure to 19% vs. 3% for non-radiated patients
• Radiation + autologous (DIEP) = favorable outcomes: Microvascular free flaps placed in radiated fields show only minor complications (wound/skin issues), with no increase in flap loss or fat necrosis
• "Autologous breast reconstruction is considered by many to be the gold standard for reconstruction in a radiated field." - Current Surgical Therapy, 14e

Part 5: Timing of Reconstruction

• Immediate reconstruction (at the time of mastectomy): Most common approach; patient awakens with reconstruction in progress; requires coordination between oncologic and plastic surgery teams; best cosmetic outcomes
• Delayed reconstruction: After completion of adjuvant therapy, especially if PMRT is anticipated and there is concern about tissue viability; allows mastectomy skin to heal first

Part 6: Complications Specific to DIEP Flap

Summary

1. The native breast skin envelope is preserved to act as the "container"
2. The DIEA-based perforator flap provides warm, living tissue without sacrificing muscle
3. Microvascular anastomosis to internal mammary vessels connects the flap's blood supply
4. Outcomes (satisfaction, natural feel, radiation tolerance) are superior to implant-based options for appropriate candidates

• Current Surgical Therapy, 14e (Cameron & Cameron), pp. 832, 844-845
• Schwartz's Principles of Surgery, 11e, p. 619
• Sabiston Textbook of Surgery (20e), pp. 1426-1428
• Recent reviews: Sinik & Collins 2024 (Challenges in Autologous Breast Reconstruction); Clark et al. 2025 (Pushing the DIEP Envelope)