Basal Cell Carcinoma

Notes

Introduction

A basal-cell carcinoma (BCC) is a slow-growing, locally invasive, malignant epidermal (basal layer) skin tumour.

Typically, a slow-growing skin lesion (over months / years) which commonly occurs on sun-exposed areas of the body. Eighty percent of BCCs occur on the head and neck. It is the commonest form of skin cancer. It is 4-5x more common than squamous cell carcinoma (SCC).

They generally affect middle-aged/elderly individuals, unless there is a genetic susceptibility (e.g. Gorlin's syndrome - see below). BCCs are locally invasive and rarely metastasize.

BCC on the face. Image courtesy of Wikipedia Commons

Risk factors

  • Male sex
  • Increasing age
  • Fitzpatrick skin types I & II (light skin, tans poorly)
  • Genetics:
    • Mutations in PTCH, p53, ras, fos
    • Albinism
    • Gorlin’s syndrome
    • Xeroderma pigmentosum
  • Carcinogens:
    • Sun exposure (UV radiation)
    • Others: ionizing radiation, arsenic, hydrocarbons
  • Immunosuppression (e.g. AIDS / transplantation)
    • 13-fold increase in 10-year incidence of non metastatic skin cancer in transplant population vs. general population

Gorlin-Goltz syndrome

Gorlin-Goltz syndrome or nevoid basal cell carcinoma syndrome (NBCCS) is a genetic condition which greatly increases the risk of developing BCCs.

A rare autosomal dominant condition that occurs as a result of gene mutation, specifically the PTCH1 gene.  Individuals with Gorlin syndrome typically begin to develop BCCs during adolescence or early adulthood.

Other clinical features include:

  • Broad nasal root
  • Hypertelorism (wide-spaced eyes)
  • Other:
    • Bifid ribs
    • Odontogenic keratocysts
    • Palmar and plantar pits in the hands
    • Calcification of the faux celebri (may be demonstrated on CT)

Clinical features

BCCs are often diagnosed clinically by the presence of a slowly enlarging skin lesion with a typical appearance.

Irregular skin lesion; typically on the face or neck. Clinical features can be remembered with the mnemonic 'TURP'.

  • T - Telangiectasia
  • U - Ulceration
  • R - Rolled edges
  • P - Pearly edge

Differential diagnoses

  • Squamous Cell Carcinoma (SCC)
  • Bowen’s disease (SCC insitu)
  • Actinic (solar) keratosis
  • Keratocanthoma
  • Amelanotic melanoma

Subtypes

  • Nodular BCC (most common, 50-60%)
  • Superficial BCC
  • Pigmented BCC
  • Morphoeic
  • Micronodular
  • Infiltrative
  • Basosquamous

Management

Management may be surgical or non-surgical and based upon a clinical-suspicion (e.g. what the lesion looks like) or upon a biopsy result (tissue diagnosis).

Surgical treatment may be 'Excisional' or 'Destructive':

  • ‘Excisional’ - e.g, wide-local excision (common treatment modality) or Moh’s Micrographic Surgery (typically reserved for high-risk lesions)
  • ‘Destructive’ - e.g. curettage and cautery, cryotherapy or carbon dioxide laser. NB - these methods do not provide a histological sample, therefore they are typically reserved for low-risk lesions only.

Non-surgical treatment:

  • Radiotherapy, may be used in:
    • Adjuvant therapy
    • Prevention of reoccurrence (e.g. incompletely excised margins)
    • Recurrent BCCs 
    • High-risks BCCs (where surgery is not appropriate)
    • NB - there is a risk of radiation-induced BCC development in patients with Gorlin’s syndrome!
  • Topical immunotherapy (Imiquimod)
  • PDT (Methyl aminoevulinate MAL-PDT)

High vs. Low-risk lesions

Lesions may be either high or low-risk.

A high-risk BCC is determined by ANY of the below:

  • Size > 2 cm
  • Site (around eyes, nose, lips and ears)
  • Poorly-defined margins
  • Histological sub-type (morpoeic, infiltrative, micronodular, basosquamous)
  • Histological features (e.g. perineural / perivascular invasion)
  • Previous treatment failure
  • Immunosuppression

Treatment selection

Generally speaking, treatments that do not permit histological confirmation (tissue diagnosis) are only used for LOW RISK lesions.

Consider patient, tumour and practitioner factors:

  • Patient - choice, co-morbidities, anti-coagulants etc.
  • Tumour - high vs. low risk
  • Practitioner - preference, experience, availability

Surgical excision margins

Surgical excision margins are based upon the British Association of Dermatologists (BAD) guidelines for BCC.

Lesions should be excised down to subcutaneous fat to ensure that the entirely of skin (epidermis and dermis) has been included in the excision sample.

  • Low-risk lesions (small <2 cm, well-defined) - 4-5 mm margin provides 95% clearance.
  • High-risk lesions (large >2cm, poorly-defined) - 5 mm margin provides 82% clearance; consider referral for Moh’s Surgery.
  • Recurrent lesions - referral to Skin MDTre-excision of scar (5-10 mm margins) or Moh’s Surgery +/- Radiotherapy.

 

Pulsenotes uses cookies. By continuing to browse and use this application, you are agreeing to our use of cookies. Find out more here.