Is curettage and electrodesiccation suitable for treating well-differentiated squamous cell carcinoma on the leg?

Treatment of Well-Differentiated Squamous Cell Carcinoma on the Leg

Curettage and electrodesiccation (C&E) may be considered for low-risk, primary squamous cell carcinoma (SCC) in non-terminal hair-bearing locations, but standard excision with 4-6 mm margins is generally recommended for SCC on the leg. 1

Risk Assessment for SCC on the Leg

When determining the appropriate treatment for well-differentiated SCC on the leg, consider:

• Low-risk features:

  • Small size (<2 cm)
  • Well-differentiated histology
  • No perineural invasion
  • No lymphovascular invasion
  • Immunocompetent patient

• High-risk features:

  • Location on lower leg (especially pretibial area)
  • Larger size (>2 cm)
  • Poor differentiation
  • Perineural invasion
  • Recurrent lesion
  • Immunosuppression

Treatment Options for SCC on the Leg

Standard Excision (Preferred Treatment)

• Recommended approach: Surgical excision with 4-6 mm margins to a depth of mid-subcutaneous adipose tissue with histologic margin assessment 1
• Provides tissue for complete histopathologic evaluation
• Allows assessment of tumor depth, differentiation, and presence of perineural invasion
• Higher cure rates compared to destructive methods

Curettage and Electrodesiccation (C&E)

• May be considered for select low-risk, primary SCCs in non-terminal hair-bearing locations 1
• Important limitations for leg location:
  • Not recommended for pretibial area due to poor healing
  • Not appropriate if subcutaneous layer is reached during procedure 1
  • Results are highly operator-dependent 1
  • Does not allow histologic margin assessment 1

Mohs Micrographic Surgery (MMS)

• Recommended for high-risk SCC 1
• Provides comprehensive margin control
• Consider for:
  • Recurrent tumors
  • Poorly defined borders
  • Location in areas with limited tissue (not typically an issue on the leg)
  • Perineural invasion

Radiation Therapy

• Can be considered when surgical options are contraindicated or refused
• Disadvantages include:
  • Lower cure rates than surgery
  • Poor healing, particularly on the leg 1
  • Cost and patient convenience issues

Treatment Algorithm for SCC on the Leg

1. For low-risk, well-differentiated SCC on the leg:

   • Standard excision with 4-6 mm margins to mid-subcutaneous fat is preferred 1
   • C&E may be considered for very small (<1 cm), superficial, well-differentiated tumors in non-pretibial locations 1

2. For high-risk SCC on the leg:

   • Mohs micrographic surgery is recommended 1
   • If MMS is unavailable, standard excision with wider margins (6+ mm) and careful histologic assessment

Important Considerations and Pitfalls

• Deep margin involvement: Most incomplete excisions (94%) involve the deep margin rather than lateral margins 2. Ensure adequate depth of excision to mid-subcutaneous fat.

• Healing concerns: The lower leg, especially the pretibial area, is prone to poor healing. This may influence treatment selection away from destructive techniques like C&E.

• Follow-up: Regular monitoring is essential as 95% of recurrences occur within 5 years 3

• Common pitfalls:

  • Using C&E when subcutaneous tissue is reached (should switch to excision) 1
  • Inadequate deep margin control (most common cause of incomplete excision) 2
  • Underestimating tumor extent, particularly on sun-damaged skin

Conclusion

While C&E may be considered for select low-risk SCCs, standard excision with 4-6 mm margins is generally the preferred treatment for well-differentiated SCC on the leg due to better margin control, complete histologic assessment, and higher cure rates. The decision should prioritize complete tumor removal to minimize recurrence risk and optimize patient outcomes.