Basal Cell Carcinoma

Background and Epidemiology

  • The most common malignancy in caucasian individuals (rare in patients with darker skin), with an incidence of up to 0.2% of the population (100-200/100,000)
  • Lifetime risk is estimated at 30%

Risk Factors/Aetiology

  • UVR exposure
    • The exact importance of duration/magnitude is unknown, so it is important to ask about any over-exposure
    • Sub-burn and overexposure as a child seems much more significant than that as an adult
  • Skin type I
  • Red/blonde hair and blue/green eyes; freckling in childhood
  • Family history
  • Previous skin cancer
  • Age
  • Immunosuppression
  • PUVA treatment
  • Rarely, genetic syndromes can predispose to BCC (i.e. basal cell naevus syndrome associated with Gorllin’s syndrome)

Pathophysiology

  • Arise from the pluripotent cells of the basal cell layer of the epidermis
  • One of the important signalling pathways thought to be dysregulated in the development of BCC is the Hedgehog-patch pathway
    • Hedgehog gene encodes an extracellular protein that binds to a cell membrane receptor complex (Patch and SMO) to start a cascade of cellular events responsible for cell proliferations
      • mutations of Patch, hedgehog and SMO, as well as other tumour suppressor genes, can all increase the risk of BCC development

Presentation and types of BCC

  • Typically occur on sun-exposed areas e.g. head and neck (80%)
  • Early lesions are small, may be translucent or pearly and have raised border with telangiectasia and an ulcerated centre (rodent ulcer)
  • Nodular
    • Solitary, shiny, red/pearly nodule with large telangiectasic vessels
      • may be cystic
      • may be ulcerated with rolled edges
    • Commonly on the face
    • Typical history is of spontaneous bleeding and healing
  • Superficial
    • Tends to occur in younger patients and at multiple sites, most commonly the upper trunk/shoulders
    • Pink/red, scaly, irregular plaques, well-demarcated and often larger than 20mm at presentation
    • Slowly grow over months/years
    • Can bleed/ulcerate
  • Morphoeic (or sclerosing/infiltrative)
    • Usually found on the face
    • Generally more aggressive
      • May infilltrate peripheral nerves and more likely to recur after surgery
    • Thickened, yellowish/skin-colour, waxy/scar like, poor demarcated plaques

Investigations/Management

  • The principle investigation is biopsy for histology.  Because BCCs are usually small and localised, surgical excision of the lesion is usually performed for both diagnostic and therapeutic purposes.
    • Surgical excision is treatment for the majority (certainly nodular BCC) of tumours
      • 4mm margin is recommended
  • Other options include
    • Mohs surgery
      • Mainly used for large (>2cm) tumours at high risk sites e.g. alar crease of the nose, near the vermillion border of the lips, on the ear etc
      • Also used for BCC recurrences
      • BCC without clear margins
    • Curettage and cautery
      • May be used for low risk BCC (small, well-defined, non-critical sites)
    • Radiotherapy
    • Topical treatments may be preferred for superficial BCC e.g.
      • imiquimod
      • topical fluorouracil 5% (body/trunk/limbs- not face)
      • cryotherapy
    • Rarely light therapy (PDT) can be used (patients are made photosensitive)

Prognosis, Prevention and follow-up

  • 5-year cure rate of about 90%
    • A minority of patients may relapse
    • (Almost no patients will ever die of BCC)
  • Make sure to advise about UV protection
  • Also ask to return early if symptoms/features recur

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