What are the characteristics and treatment options for suspicious skin lesions, such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), with unusual appearance?

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Last updated: November 13, 2025 • View editorial policy

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Characteristics and Treatment of Suspicious Basal Cell and Squamous Cell Carcinomas

For suspicious skin lesions concerning for BCC or SCC, perform a biopsy that includes deep reticular dermis to capture any infiltrative histology at deeper margins, then select treatment based on risk stratification—with surgery (particularly Mohs for high-risk features) providing the best cure rates, though superficial BCC and SCC in situ may be treated with topical therapies when surgery is impractical. 1

Clinical Appearance and Recognition

Basal Cell Carcinoma Characteristics

  • Classic presentation: Shiny, pearly papule with smooth surface, rolled borders, and arborizing telangiectatic vessels 2
  • Alternative presentations: May appear as plaque-like lesions with waxy, translucent appearance, often with ulceration and telangiectasia 3
  • "Unusual" BCCs can be difficult to assess clinically in high-risk populations, warranting a low threshold for biopsy 1

Squamous Cell Carcinoma Characteristics

  • Typical appearance: Firm, smooth, or hyperkeratotic papule or plaque with possible central ulceration 2
  • Evolution: Arises from keratotic patches (actinic keratoses) and becomes more nodular and erythematous with growth, sometimes including keratin plugs, horns, or ulceration 3

Assessment Using ABCDE Rule

The ABCDE criteria should be applied to evaluate suspicious lesions 1, 4:

  • Asymmetry: Irregular shapes or halves that don't match
  • Border irregularity: Jagged, notched, or blurred edges
  • Color heterogeneity: Multiple colors or uneven distribution
  • Diameter: Greater than 6 mm (though many melanomas are now <5 mm) 1
  • Evolving: Changes in size, shape, color, or symptoms over time

Critical caveat: The "ugly duckling" sign—lesions that look different from surrounding lesions—should raise suspicion even if ABCDE criteria are not fully met 4

Diagnostic Workup

Initial Evaluation

  • Complete skin examination is mandatory for BCC (entire skin surface) 1
  • Complete skin AND regional lymph node examination for SCC due to metastatic potential 1
  • Full skin examination is essential because patients often have concurrent precancers or cancers at other sun-exposed sites and increased melanoma risk 1

Biopsy Technique

The biopsy must include deep reticular dermis if the lesion appears more than superficial 1. This is critical because:

  • Infiltrative histology may only be present at deeper, advancing tumor margins
  • Superficial biopsies frequently miss this aggressive component
  • The histologic subtype at depth determines risk stratification and treatment selection

Technique selection 2:

  • Shave biopsy if the lesion is raised
  • Punch biopsy of the most abnormal-appearing area if flat

Pathology Requirements

The histology report must include 1:

  • Histologic subtype and growth pattern
  • Presence of infiltrative components
  • Perineural invasion
  • Tumor depth/thickness
  • Margin clearance status

Additional Workup for SCC

If palpable or abnormal lymph nodes are present 1:

  • Fine-needle aspiration (FNA) for diagnosis
  • If head/neck nodes are FNA-negative: consider repeat imaging, repeat FNA, or open biopsy
  • If trunk/extremity nodes are FNA-positive: perform imaging as indicated
  • If trunk/extremity nodes are FNA-negative: proceed to open biopsy

Risk Stratification

High-Risk Features (Both BCC and SCC)

Features indicating aggressive behavior and higher recurrence/metastasis risk 1, 2:

  • Large size or ill-defined borders
  • Aggressive histologic patterns (infiltrative, morpheaform, basosquamous for BCC)
  • Perineural invasion
  • Location in high-risk anatomic sites (face, ears, genitals)
  • Recurrent tumors
  • Immunosuppression

BCC-Specific Considerations

  • Superficial BCC has excellent prognosis and multiple treatment options 1
  • Nodular and morpheaform (fibrosing/sclerosing) subtypes require more aggressive treatment 5

SCC-Specific Considerations

  • Poorly differentiated tumors carry higher risk 1
  • Tumors arising in chronic wounds, scars, or areas of chronic inflammation have increased metastatic potential 6

Treatment Options

Surgical Approaches (Best Cure Rates)

Surgery provides the best results in evidence-based reviews 1, though functional and cosmetic considerations may favor other modalities 1.

Mohs Micrographic Surgery

  • Lowest recurrence rate among all treatments 2
  • Best reserved for: Large, high-risk tumors or tumors in sensitive anatomic locations (face, ears, genitals) 2
  • Provides complete circumferential peripheral and deep-margin assessment (CCPDMA) 1

Standard Surgical Excision

  • Appropriate for smaller, lower-risk tumors 2
  • Requires postoperative margin assessment (POMA) 1

Curettage and Electrodesiccation

Effective for low-risk tumors with three critical caveats 1:

  1. Do NOT use on hair-bearing sites: Tumor may extend down follicular structures and not be adequately removed
  2. If subcutaneous fat is reached during surgery: Must convert to surgical excision, because the curette cannot distinguish soft tumor from even softer subcutaneous fat
  3. Only appropriate for low-risk lesions with well-defined borders

Topical Therapies (For Superficial Lesions)

5-Fluorouracil (FDA-Approved)

  • Indicated for: Multiple actinic keratoses and superficial BCC when conventional methods are impractical 7
  • Success rate: Approximately 93% for superficial BCC based on 113 lesions 7
  • Critical limitation: Diagnosis must be established prior to treatment; not proven effective for other BCC subtypes 7
  • Surgery remains preferred for isolated, easily accessible BCC (nearly 100% success) 7

Imiquimod (FDA-Approved)

For superficial BCC 5:

  • Dosing: 5 times per week for full 6 weeks
  • Wash treatment area 8 hours after application
  • Most patients experience erythema, edema, induration, erosion, scabbing/crusting, and flaking at application site 5
  • Not established for: Nodular or morpheaform BCC subtypes 5
  • Not established for: sBCC on face, head, or anogenital areas 5

For actinic keratoses 5:

  • Dosing: 2 times per week for 16 weeks
  • Wash treatment area 8 hours after application

Important warnings 5:

  • Can cause intense local inflammatory reactions requiring dosing interruption
  • Minimize sun exposure during treatment (heightened sunburn susceptibility)
  • Regular follow-up required to assess treatment outcome after skin reactions resolve

Radiation Therapy

  • Alternative to surgery when function, cosmetic outcome, or patient preference favor non-surgical approach 1
  • May be chosen to achieve optimal overall results despite surgery having better cure rates 1

Cryosurgery

  • Option for smaller, lower-risk tumors 1, 2
  • Higher recurrence rates than surgical excision 8

Critical Treatment Selection Algorithm

For superficial BCC or SCC in situ with multiple lesions or difficult treatment sites 7, 5: → Consider topical 5-fluorouracil or imiquimod

For isolated, easily accessible low-risk BCC or SCC 1, 2: → Surgical excision, electrodesiccation and curettage, or cryotherapy

For high-risk features (large size, ill-defined borders, aggressive histology, perineural invasion, sensitive locations) 1, 2: → Mohs micrographic surgery (lowest recurrence rate)

For patients where surgery is contraindicated or refused 1: → Radiation therapy (though cure rates are lower than surgery)

Common Pitfalls to Avoid

  1. Superficial biopsies: Always include deep reticular dermis to avoid missing infiltrative components at tumor base 1

  2. Using curettage on hair-bearing sites: Tumor extends down follicles and will not be adequately removed 1

  3. Continuing curettage into subcutaneous fat: Must convert to excision when fat is reached 1

  4. Assuming all BCCs are low-risk: Nodular and morpheaform subtypes require aggressive treatment; topical therapies are not appropriate 5

  5. Inadequate lymph node assessment for SCC: Regional nodes must be examined; palpable nodes require FNA 1

  6. Treating without histologic confirmation: Particularly important before using topical therapies, as they are only effective for specific subtypes 7, 5

  7. Extending topical treatment beyond recommended duration: Imiquimod for sBCC should not exceed 6 weeks; for AK should not exceed 16 weeks 5

Follow-Up Considerations

  • Five-year risk of subsequent skin cancer after index keratinocyte carcinoma: 41% 2
  • After more than one diagnosis: Five-year risk increases to 82% 2
  • Regular monitoring for recurrence is essential, though no clear guidelines exist for follow-up intervals 2
  • Patients with sBCC treated with imiquimod require regular follow-up to re-evaluate the treatment site 5

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

4
Guideline

Skin Mole Assessment for Breast Cancer Survivors

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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