How to diagnose basal cell (BCC) or squamous cell carcinoma (SCC) in a skin lesion without distinctive coloration?

Diagnosing Basal Cell and Squamous Cell Carcinoma Without Distinctive Coloration

A skin biopsy is the definitive method to diagnose basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) when lesions lack distinctive coloration. The biopsy should include deep reticular dermis to ensure proper evaluation of potential infiltrative components 1.

Clinical Evaluation Before Biopsy

When evaluating skin lesions without distinctive coloration that might be BCC or SCC:

Physical Examination Features

• For BCC: Look for shiny, pearly papules with smooth surfaces, rolled borders, and arborizing telangiectatic vessels 2
• For SCC: Look for firm, smooth or hyperkeratotic papules/plaques, possibly with central ulceration 2
• Additional concerning features:
  • Ulceration
  • Bleeding
  • Inflammation
  • Border irregularity
  • Evolution over time 1

Advanced Diagnostic Tools

• Dermoscopy/Dermatoscopy: Can improve clinical diagnosis even without pigmentation 3

  • BCC dermoscopic criteria: arborizing vessels, maple-leaf like structures, ulceration, spoke-wheel structures 3
  • Non-pigmented SCC features: pink-white areas, multiple erosions, fine vessels 3

• Reflectance Confocal Microscopy (RCM): For specialized centers, can help evaluate:

  • For BCC: basaloid tumor islands/nests/silhouettes
  • For SCC: keratin pearls, areas where lesion bulges into dermis 1

Biopsy Techniques

Recommended Biopsy Methods

1. Punch biopsy: Provides adequate depth for histological evaluation
2. Shave (tangential) biopsy: Appropriate for raised lesions
3. Excisional biopsy: Complete removal of suspicious lesion 1

Important Biopsy Considerations

• Depth: Must include deep reticular dermis to detect infiltrative patterns 1
• Sample adequacy: Ensure sufficient tissue to evaluate histologic subtype and depth 1
• Location: Biopsy the most abnormal-appearing area of the lesion 2

Post-Biopsy Evaluation

Histopathological Assessment

The pathology report should include:

• Confirmation of malignancy
• Maximum tumor thickness (for SCC)
• Assessment of excision margins
• Presence of ulceration
• Presence of perineural invasion 1

High-Risk Features to Note

• Perineural invasion
• Aggressive histologic patterns
• Ill-defined borders
• Prior history of skin cancer 2

Common Pitfalls to Avoid

1. Superficial sampling: Infiltrative histology may only be present at deeper margins and missed with superficial biopsies 1

2. Relying solely on clinical appearance: Non-pigmented lesions can be particularly challenging to diagnose without histopathological confirmation 1

3. Inadequate follow-up: Patients with one skin cancer have a 41% five-year risk of subsequent skin cancer; this increases to 82% after more than one diagnosis 2

4. Overlooking high-risk populations: Immunosuppressed patients and those with prior skin cancers require a lower threshold for performing biopsies 1

For lesions in cosmetically sensitive areas, consider that while cytological examination (scraping technique) may provide rapid preliminary diagnosis, it cannot replace histopathological confirmation which is mandatory before treatment 4.