Basal Cell Carcinoma (BCC)

Prevalence:

• Most Common Skin Cancer: Accounts for approximately 75% of skin cancer cases.
• Low Metastatic Potential: Rarely metastasizes.
• Alternative Name: Also known as “rodent ulcer.”
• Type: Classified as a non-melanoma skin cancer.

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Risk Factors

Skin Type:

• Type I: Individuals with fair skin, blonde or red hair, and blue or green eyes are at higher risk and tend to burn very easily.

Sun Exposure:

• UV Radiation: Primarily UVB, with some contribution from UVA exposure.
• Childhood Sunburns: History of blistering sunburns during childhood increases risk.
• Cumulative Exposure: Long-term sun exposure over the years.
• Geographic Factors: High sunlight exposure areas (e.g., Australia, Hawaii, Florida).

Personal History:

• Previous BCC: A history of BCC significantly increases the risk of recurrence.
• Immunocompromised Conditions: Conditions like Xeroderma pigmentosum.
• Environmental Exposures: Arsenic or x-ray exposure.

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Clinical Presentation

Nodular BCC:

• Appearance: Shiny, pearly papules with prominent dilated blood vessels (telangiectasias) visible under the skin.
• Color: Usually flat and paler than the surrounding skin, often pearly or translucent with possible telangiectasias on the surface.
• Progression: Can develop into an ulcer with raised, rolled edges (rodent ulcer).
• Common Site: Typically found on the bridge of the nose, where eyeglasses sit.

Differential Diagnoses for Nodular BCC:

• Intradermal Nevus: Lacks the characteristic shiny and stretched appearance of BCC.
• Squamous Cell Carcinoma (SCC): Typically appears on more severely damaged skin and lacks translucency.

Superficial BCC:

• Appearance: Red plaques with possible atrophy and pigment dots, generally well-circumscribed with a raised edge, less shiny.
• Common Sites: Often found on the back, arms, legs, and behind the ears.
• Prevalence: The most common form of BCC.

Differential Diagnoses for Superficial BCC:

• Eczema: Characterized by a weepy, fissured surface and itchiness, typically found in atypical locations for BCC.
• Psoriasis: Distinguished by a silvery scale.
• Bowen’s Disease: Has a duller surface with more hyperkeratosis.

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Additional Characteristics

• Advanced Lesions: May ulcerate, leading to rodent ulcers.
• Bleeding and Poor Healing: Lesions may bleed easily and are often associated with oozing or crusting.
• Distribution: Predominantly appears in areas exposed to UV radiation.
  • Face: Especially around the nose.
  • Trunk and Limbs: Less common but possible.
• Growth and Invasion: Although metastasis is rare, untreated BCCs can invade surrounding tissues.
• Recurrence Risk: Estimated at 1-10%.

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Treatment Options

• Excision:
  • Recommended Surgical Margins Based on Risk Level
    • Low-Risk Tumours: 2–3 mm margin.
    • High-Risk Tumours: Greater than 5 mm margin.
    • Rationale: Surgical margins are tailored to balance complete tumour excision with preservation of normal tissue, particularly in cosmetically or functionally significant areas.
• Mohs Surgery:
  • Best for recurrent BCCs
  • Ensures adequate removal, especially for mid-face lesions
• Shave Excision & Curettage:
  • Followed by electrocautery, desiccation, or diathermy
• Cryotherapy:
  • Using double-freeze thaw technique or thermocouple to ensure temperature at the lesion base is -30ºC or colder
• Cytotoxic Agents:
  • 5-Fluorouracil (less effective than imiquimod cream)
• Curettage and Electrodessication:
  • Scrapes away cancer and uses electricity to kill remaining cancer cells
  • Usually for older patients
• Imiquimod (Aldara) Cream:
  • Immune response modifier inducing cytokines involved in cell-mediated immunity
  • Treats superficial BCC with a 90% success rate
  • Good cosmetic effects
  • Side effects: Flu-like symptoms, inflammation, and discomfort in treated areas
• Photodynamic Therapy:
  • Apply photosensitizing cream (5-ALA, Metvix) and cover for 3-5 hours
  • Area exposed to appropriate wavelength light to activate the sensitizer → forms reactive oxygen species
  • Good cosmetic effects
  • Side effects: Blistering, swelling, pain, crusting, slight hypopigmentation
• Ablative Laser Therapy
• Adjuvant Therapies:
  • Chemotherapy
  • Radiation: Targets spread to other organs/lymph nodes or for tumors that can’t be treated with surgery