Basal Cell Carcinoma

Basal Cell Carcinoma

BCCs arise from pluripotent cells found in the basal layer of the epidermis or follicular structures. These cells are the origin of hair, sebaceous glands, and apocrine glands. The source of the tumour is usually the epidermis and occasionally the outer root sheath of a hair follicle. BCCs are locally aggressive tumours that rarely metastasise.

If left untreated, BCC can cause clinically significant morbidity. Because this cancer is associated with sun exposure it is often found on the head and neck - causing cosmetic disfigurement. Lesions in the orbital area can even result in loss of sight. Peri-neural spread can result in loss of nerve function, as well as deep invasion. Occasionally the lesions can provide a nidus for infection. Death from BCC, however, is extremely rare.

 Approximately 50% of BCC occurs on the head and the neck, 27% on the trunk, 13% on the upper limbs and 8% on the lower limbs11.

BCC Epidemiology and Incidence

Incidence

  • BCC is the most common malignancy in humans and global incidence per 100,000 is presented in the Figure below.
  • In 2002 a National Non-Melanoma Skin Cancer Survey in Australia estimated that 256,000 (884/100,000) were treated for BCC, which represented a 35% rise since 19857.
  • Annual incidence in the US is approximately 900,000 cases (comprising 550,000 males and 350,000 females). Age-adjusted incidence per 100,000 Caucasians is 475 cases for males and 250 for females. The estimated lifetime risk of BCC in male Caucasians is 33-39% compared with 23-28% in females.
  • In the US, a comparison of BCC incidence between 1979-1980 and 1993-1994 found that there was a 80% increase in both males and females12. 

Global BCC incidence

Risk Factors

Risk factors for the development of BCC include:

  • Disorders associated with increased sun sensitivity (e.g. albinism and xeroderma pigmentosum),
  • Exposure to ionising radiation (e.g. X-rays or UV light),
  • Arsenic and carcinogens,
  • Immunosuppression and skin damage (burns and scars).
  • Incidence increases with age, and in people with fair/freckly skin.


Clinical Features of BCC

Early stage BCCs appear as translucent papules or nodules with a smooth surface and a few dilated vessels under a thin epidermis.

There are two common forms of BCC, nodular and superficial. There is also a rarer form of BCC called morphea-like, sclerodermiform or fibrosing BCC:

  • Nodular BCC (nBCC)
    • The most common form of BCC.
    • Tumour resembles a smooth, round waxy pimple, it is yellow or grey and variable in size.
    • The tumour may appear depressed in the middle with ulceration.
    • Inside the nodule the blood vessels are chronically dilated - a condition known as telangiectasia.
    • Large tumours are quite distinctive and easily diagnosed; smaller tumours are more difficult to differentiate.

  • Superficial BCC (sBCC)
    • Occurs most commonly on the upper trunk, shoulders, face and neck.
    • sBCCs that occur outside of the H-zone of the face are classified as low risk.
    • sBCCs are progressively spreading, slow-growing cancers.
    • Lesions are typically red, with a slight raised, ulcerated or crusted surface.

  • Morphea-like, sclerodermiform or fibrosing BCCs
    • An uncommon type of BCC.
    • Occurs mostly on the face. 
    • Lesion appears as a flat or slightly depressed, shiny, hard, yellow-white patch with irregular borders.
    • Can be difficult to remove because of root-like projections under the skin

Diagnosing BCC

81% of BCC diagnosis is by histological examination, although many BCC tumours can be recognised macroscopically9.

Treating BCC

Options include:

  • Photodynamic therapy (PDT) - Metvix® - PDT.
  • Cryotherapy.
  • Surgical approaches:
    • Curettage and electrodesiccation.
    • Elliptical excision.
    • Excision and reconstructive surgery.
    • Mohs' micrographic surgery
  • Radiotherapy.
  • Topical therapy.
    • 5% Imiquimod cream.

For further information on these therapies click here (by clicking on this link you will be leaving this site - Galderma is not responsible for the content).

References