What are the steps for the excision of basal cell carcinoma?

Steps for Excision of Basal Cell Carcinoma

Standard surgical excision with appropriate margins is the cornerstone of basal cell carcinoma treatment, with Mohs micrographic surgery being the preferred approach for high-risk tumors to maximize cure rates and minimize recurrence. 1

Pre-Excision Assessment

• Determine tumor risk factors:

  • Location (high-risk areas: face, especially nose, ears, lips)
  • Size (>2cm considered high-risk)
  • Histological subtype (infiltrative, morpheaform, micronodular are high-risk)
  • Previous recurrence
  • Immunosuppression status 1

• Consider preoperative biopsy if diagnosis is uncertain or to determine histological subtype 2

Surgical Approach Selection

For Low-Risk BCCs:

• Standard excision with 4mm margins for:
  • Well-defined, primary nodulocystic BCCs <2cm in diameter
  • Located on trunk or extremities
  • Non-aggressive histological subtypes 2, 1

For High-Risk BCCs:

• Mohs micrographic surgery (preferred) for:

  • Facial lesions, especially in high-risk areas
  • Recurrent tumors
  • Aggressive histological subtypes
  • Poorly defined clinical margins
  • Perineural involvement 2, 1

• If Mohs surgery is unavailable, use excision with complete circumferential peripheral and deep margin assessment (CCPDMA) with wider margins (6-10mm) 2, 1

Excision Procedure Steps

1. Mark surgical margins:

   • 4mm for low-risk BCCs
   • 5-10mm for high-risk or recurrent BCCs 2, 3
   • Include any peripheral erythema in the excision 2

2. Administer local anesthesia:

   • 1-2% lidocaine with epinephrine (except in end-arteriole areas)

3. Perform excision:

   • Make incision through epidermis and dermis to subcutaneous fat
   • Include underlying fascia if tumor appears to invade deeply
   • Orient specimen for pathologist (typically with suture marker)

4. Assess margins:

   • For standard excision: Send specimen for postoperative margin assessment
   • For Mohs surgery: Process tissue for immediate microscopic examination of 100% of margins 2
   • If using frozen section control, ensure complete assessment of all deep and peripheral margins 2

5. Wound management:

   • If standard excision with postoperative margin assessment:

     • Consider delaying closure until pathology report if high-risk features 2
     • For simple closures: primary side-to-side closure, skin grafting, or secondary intention healing 2

   • If tissue rearrangement or skin graft is necessary:

     • Intraoperative surgical margin assessment is essential before reconstruction 2, 1

Special Considerations

• Curettage and electrodesiccation may be used for select low-risk tumors with these caveats:

  • Avoid on hair-bearing sites
  • Switch to excision if subcutaneous layer is reached
  • Review biopsy results to ensure no high-risk features 2

• Incomplete excision management:

  • Re-excision is strongly recommended, especially for:
    • Tumors in critical midfacial sites
    • Deep margin involvement
    • Aggressive histological subtypes
    • Repairs using flaps or grafts 1
  • 21-41% of incompletely excised BCCs will recur if not re-excised 2

• For recurrent BCC:

  • Mohs surgery is strongly preferred with 5-year recurrence rate of only 5.6% compared to higher rates with standard excision 2, 1
  • If Mohs is unavailable, use wider margins (5-10mm) 2

Post-Excision Care

• Wound care instructions
• Suture removal typically in 5-14 days (depending on location)
• Histopathology review
• Long-term follow-up is essential as 56% of recurrences occur beyond 5 years 1

Common Pitfalls to Avoid

• Underestimating margins for high-risk tumors, especially on the nose and ears where incomplete excision rates can reach 50-61.5% for aggressive subtypes 4
• Failing to identify subclinical extension, particularly in morpheaform and infiltrative subtypes
• Inadequate follow-up (recurrences can occur beyond 5 years) 1
• Not considering Mohs surgery for recurrent tumors (standard excision has inferior cure rates for recurrent disease) 2

By following these structured steps and considering the specific characteristics of each basal cell carcinoma, optimal outcomes with minimal recurrence rates can be achieved.