Sunlight-induced skin damage is on the rise everywhere. The earth’s protective ozone
layer, which acts as a UV sunlight filter, has shrunk dramatically in recent decades,
exposing us to increasing levels of UV radiation. Also, the trend toward increased
leisure time means more time spent on outdoor recreational activities. And of course,
tanning is as fashionable as ever, making overexposure to the sun a purposeful pastime.
UV radiation is a serious health threat. The incidence of skin cancer has exploded
in recent decades. In fact, cancerous skin tumours are now the most common cancers
affecting humans.
Skin Tumours
Not all skin tumours are deadly. There are two main categories of skin tumours: benign
and malignant. Benign tumours can be annoying, but they are not life-threatening.
They often remain for years without changing, or they may regress spontaneously.
Malignant tumours, on the other hand, grow rapidly and invade other parts of the
body (metastasize).
Benign tumours
Benign skin tumours are minimally invasive, with the potential exception of actinic
keratosis. Sun exposure triggers their occurrence (except for warts).
Warts or Papillomas are raised, well-defined growths with bumpy,
gray surfaces. The human wart virus is transmitted via direct skin-to- skin contact.
Warts are removed by freezing, salicylic acid plasters, or specially formulated
over-the-counter treatments.
Seborrheic Keratosis, the most common type of tumour in the elderly,
affects the oily areas of the trunk, shoulders, face, and scalp. Sun exposure is
a predisposing factor in the development of this type of growth. Lightly raised
on the skin, the tumour is clearly circum- scribed, rough, and warty, and is sometimes
covered with a greasy crust. Treatment is usually unnecessary except for cosmetic
purposes. These growths usually go away naturally, but may recur.
Keratoacanthoma a rapidly growing benign tumour, often resembles
squamous cell carcinoma and is therefore usually removed for pathological examination.
These tumours occur most often in the middle to later years. Areas of extended sun
exposure are the most common locations.
Actinic Keratosis Lesions are pre-malignant. They appear rough and
red-to-brown in colour, and usually affect persons with fair skin. Actinic keratosis
lesions appear on areas of high sun exposure, e.g., the scalp, nose, and ears. Although
they may disappear spontaneously, treatment is usually required because the lesions
often indicate squamous cell carcinoma. They can be surgically removed, frozen,
or treated with topical chemotherapy.