Basal cell carcinoma (skin)
D E F I N I T I ON
Commonest form of skin malignancy; also known as a ‘rodent ulcer’.
AET IOLOGY
Prolonged sun exposure or UV radiation.
Associated with abnormalities of the patched/hedgehog intracellular signaling cascade,
as seen in Gorlin’s syndrome (naevoid basal cell carcinoma syndrome). Other risk factors
include photosensitizing pitch, tar and arsenic.
Pathophysiology: Small dark blue staining basal cells growing in well-defined aggregates
invading the dermis with the outer layer of cells arranged in palisades. Numerous mitotic
and apoptotic bodies are seen. Growth rate is usually slow, but steady and insidious.
It does not metastasize, but has the potential to invade and destroy local tissues.
E P IDEMI OLOGY
Common in those with fair skin and areas of high sunlight exposure,
common in the elderly, rare before the age of 40 years. Lifetime risk in Caucasians is 1:3.
H ISTORY
A chronic slowly progressive skin lesion usually on the face but also on the scalp,
ears or trunk.
EXAMI N A T ION
Nodulo-ulcerative (most common): Small glistening translucent skin over a coloured
papule that slowly enlarges (early) or a central ulcer (‘rodent ulcer’) with raised pearly
edges. Fine telangiectatic vessels often run over the tumour surface. Cystic change may be
seen in larger more protuberant lesions.
Morphoeic: Expanding, yellow/white waxy plaque with an ill-defined edge (more
aggressive).
Superficial: Most often on trunk, multiple pink/brown scaly plaques with a fine ‘whipcord’
edge expanding slowly; can grow to more than 10 cm in diameter.
Pigmented: Specks of brown or black pigment may be present in any type of basal cell
carcinoma.
I N V E S T IGATIONS
Biopsy is rarely necessary (diagnosis is based mainly on clinical
suspicion).
MANAGEMENT
Cryotherapy, curettage, cauterization and photodynamic therapy are
used for small superficial lesions.
Surgical: Excision with a 0.5 cm margin of surrounding normal skin for discrete nodular or
cystic nodules in patients under 60 years; Mohs’ micrographic surgery, which includes
careful review of tissue excised under frozen section, is the treatment of choice for large
tumours (1 cm diameter) and lesions near the eyes, nose and ears. Excision and skin flap
coverage may be necessary.
Radiotherapy: Useful in basal cell carcinomas involving structures that are difficult to
surgically reconstruct (e.g. eyelids, tearducts). Repeated treatments may be necessary
as there is risk of side effects such as radiation dermatitis, ulceration or depilation.
COMPL I C A T IONS
The tumour has a slow but relentless course. Can become disfiguring
on the face. Has the potential to invade, lead to loss of vision in the orbital region.
P ROGNOS I S
Good with appropriate treatment. If left, may continue to grow, invade and
ulcerate. Regular follow-up is necessary to detect local recurrence or other lesions
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