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BASAL CELL CARCINOMA

Overview

  • Commonest skin cancer

  • Most common malignancy of the eylid

  • Risk factors:

    • Fitzpatrick skin type​

    • Sun exposure

    • Advancing age

    • Immunosuppression

    • Carcinogen exposure - UV and ionising radiiation, arsenic, hydrocarbons

    • Genetic mutations

      • PTCH gene coding mutations for the sonic hedgehog signalling pathway

      • p53 tumour suppressor gene mutations​​

      • ras and fos oncogene mutations

      • Albinism

      • Naevoid basal cell syndrome (Gorlin's syndrome)

        • Autosomal dominance​

        • Chromosome 9q22.3-q31

        • Multiple basal cells, odontogenic keratocysts, palmar and plantar bits, calcifications of falx cerebri, bifid ribs, hypertelorism, broad nasal root

      • Xeroderma pigmentosum​

        • Autosomal recessive​

        • Impaired DNA repair mechanism

        • Intolerance to UV radiation

        • Multiple epithelial malignancies

    • Premalignant lesions​​

      • Naevus sebaceous of Jadassohn​

        • Present at birth on scalp or face​

        • Well-circumscribed, hairless, yellowish plaque that becomes verrucous and nodular at puberty

        • 10-15% malignant degeneration to BCC

  • Originates from pluripotential epithelial cells of epidermis and hair follicles (basal keratinocystes) at the dermoepidermal junction​​​

Overview

Prognostic factors

  • Size -  higher risk with increasing size

  • Site - high risk if central face, eyes, nose, lips or ears

  • Margins - higher risk with poorly defined margins

  • Histological subtype

  • Histological features - high risk features include perineural or perivascular invasion

  • Failure of previous treatments - high risk if recurrent lesions

  • Immunosuppresion

High-risk factors

Types of BCC

  • 26 identified subtypes

  • Large proportion of BCCs are of mixed patterns

  • ​Nodular​

    • Most common​

    • Well defined borders, flesh-coloured, pearly nodule with overlying telangeictasias

    • May be ulcerated

  • Superficial spreading​

    • Second most common type​

    • Confined to epidermis, no dermal invasion

    • Flat, pink, scaly patches with ulceration and crusting

    • Often mistaken for fungal infection, actinic keratosis, psoriasis or eczema

  • Micronodular​

    • 15% of BCCs​

    • Small rounded nodules of tumour

  • Infiltrative​

    • 7% of BCCs​

    • Opaque yellow-white colour, ill-defined

    • Tumour islands of variable size with jagged configuration

  • Pigmented

    • 6% of BCCs​

    • Pigmentation from melanin

  • Morphoeic

    • 2-3% of BCCs​

    • Most aggressive subtype

    • Indurated, flat, slightly elevated papule or plaque with scar-like appearance

    • High incidence of positive margins after excision

Types of BCC

Treatment

  • Destructive nonsurgical

    • Imiquimod 5% (Aldara) or 5-fluorouracil cream​

      • For multiple, low-risk superficial BCC and SCC in situ​

    • Photodynamic therapy​

      • Good treatment for primary superficial BCC, reasonable treatment for nodular BCC​

      • 5-amino-laevulinic acid or methylamino-laevulinic acid creams are used as photosensitising agents

    • Radiotherapy​

      • Good treatment

      • For nonsurgical candidates​

      • Delivered in fractionated doses involving orthovoltage x-rays or electron beam

      • Cure rate of primary lesions 92%

      • Risk of osteitis and skin necrosis

  • Destructive surgical​​

    • Curettage and cautery​

      • Removes visible tumour and electrodessication of residual cells​

      • For low-risk BCC

      • Based only on appearance of tumour

      • Healing by secondary intention

      • Residual tumour in 33%

      • 5-year cure rate 92.3% for primary BCC, and 60% for recurrent BCC

    • Cryosurgery

      • Destruction of BCC using effects of extreme cold (-50-60°C) from liquid nitrogen​

      • Single or multiple freeze/thaw cycles

      • For low-risk BCC

      • 5-year cure rate 99%

      • Generally heal well with minimal tissue contraction

    • Carbon dioxide laser​

      • Ablation using carbon dioxide laser may be effective for low-risk BCC​​

Treatment

Incomplete excision

  • High-risk lesions and incompletely excised deep margins are at high risk of recurrence

  • Incompletely excised peripheral margin - 17%

  • Incompletely excised deep margin - 33%

Incomplete excision
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