Evaluation and Management of Skin Cancer Lesion with Surrounding Erythema
Any peripheral rim of erythema around a squamous cell carcinoma must be included in what is assumed to be the tumor when planning excision margins 1. This is a critical distinction that directly impacts surgical planning and outcomes.
Initial Diagnostic Approach
Clinical Examination
Perform a complete skin and regional lymph node examination 1. For the lesion itself, document:
- Size and borders: Measure the lesion including any surrounding erythema
- Surface characteristics: Look for ulceration, scaling, or pearly appearance
- Vascular patterns: Note telangiectasias or other vessel patterns
- Texture: Assess for firmness, nodularity, or hyperkeratosis
Biopsy Technique
Perform a deep shave biopsy or punch biopsy that includes deep reticular dermis 1. This is essential because:
- Superficial biopsies may miss infiltrative components present only at deeper margins
- The biopsy must be deep enough to assess tumor thickness and invasion depth
- Include the most abnormal-appearing area in your sample
The histopathology report must document 2:
- Tumor thickness and differentiation
- Presence of perineural or vascular invasion
- Lateral and deep margin status
- For SCC: depth of invasion (Clark level or millimeters)
Distinguishing BCC from SCC
Clinical Clues
Basal Cell Carcinoma typically presents as:
- Pearly white, dome-shaped papule with prominent telangiectatic vessels 3, 4
- Smooth surface with rolled borders
- May have central ulceration
Squamous Cell Carcinoma typically presents as:
- Firm, smooth, or hyperkeratotic papule or plaque 3, 4
- Often with central ulceration
- Peripheral rim of erythema is characteristic and must be considered part of the tumor 1
Histologic Differentiation
If morphology is ambiguous, immunohistochemistry can help:
- Ber-EP4: Strongly positive in BCC (diffuse staining), negative in SCC 5
- MOC-31: Positive in BCC, sporadically reactive in SCC 6
- bcl-2: Diffusely positive in most BCCs, only focally reactive in some SCCs 5
Risk Stratification
High-Risk Features Requiring Aggressive Management
For both BCC and SCC 1:
- Location on central face, ears, or genitalia
- Diameter >2 cm (or >1 cm on high-risk sites)
- Poorly defined clinical borders
- Recurrent tumors
- Aggressive histologic subtypes (infiltrative, morpheaform, basosquamous for BCC; poorly differentiated, adenoid, adenosquamous, desmoplastic for SCC)
- Perineural invasion
- Immunosuppressed patients
Additional high-risk features for SCC 1:
- Invasion into deep reticular dermis or subcutaneous fat (Clark level IV/V)
- Tumor depth >4 mm
- Rapid growth
- Neurologic symptoms in the region
Treatment Algorithm
Low-Risk Tumors
Excision with 4-6 mm clinical margins 1:
- For SCC: Use 4-6 mm margins (wider than BCC due to erythema inclusion requirement)
- For BCC: 4 mm margins are adequate for tumors <2 cm
- Critical: Include any peripheral erythema in the excision for SCC 1
- Perform postoperative margin assessment
- Alternative: Curettage and electrodesiccation (avoid on hair-bearing sites and if subcutaneous fat is reached) 1
High-Risk Tumors
Mohs micrographic surgery or excision with complete circumferential peripheral and deep margin assessment is the treatment of choice 1, 7, 1:
- Mohs surgery achieves 99% 5-year cure rate for primary BCC and 98.6% for facial BCC 7
- For recurrent BCC: 94.4-96% 5-year cure rate 7
- If Mohs unavailable, standard excision with intraoperative frozen section assessment of ALL margins is required 1
Management of Positive Margins
If margins are positive after initial excision 7:
- Re-excision is strongly recommended, especially for:
- Midfacial locations
- Deep margin involvement
- Wounds closed with flaps or grafts
- Aggressive histologic subtypes
- Recurrence rates with observation alone: 30-41% at 2-5 years 7
- Residual tumor found in 45-55% of re-excisions 7
Regional Lymph Nodes (SCC)
If palpable or abnormal lymph nodes are present 1:
- Perform FNA for diagnosis
- If FNA negative in head/neck: Consider repeat FNA, imaging, or open biopsy
- If FNA positive: Obtain imaging to assess extent
- Surgery is primary treatment for resectable nodal disease in curative settings 8
Critical Pitfalls to Avoid
- Do not underestimate the extent of SCC: The erythema is tumor, not just inflammation 1
- Do not perform superficial biopsies: You will miss infiltrative components and cannot assess depth 1
- Do not use curettage if you reach subcutaneous fat: Switch to excision immediately 1
- Do not observe incompletely excised tumors on the face: Re-excise or use Mohs surgery 7
- Do not close complex defects before confirming clear margins: Use intraoperative assessment if tissue rearrangement is needed 1
Follow-Up
After treatment of an index keratinocyte carcinoma, the 5-year risk of subsequent skin cancer is 41%, increasing to 82% after a second diagnosis 3. Regular surveillance is essential, though specific intervals are not definitively established in guidelines.