Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand,1997.
Freckles are small flat brown marks arising on the face and other sun exposed areas. They are most often seen in fair skinned people, especially those with red hair, but they are an inherited characteristic that sometimes affects darker skin types as well.
The medical term for this type of freckle is ephelis (plural ephelides). The colour is due to pigment accumulating in the skin cells (keratinocytes).
Skin pigment (melanin) is made by cells called melanocytes. They don't produce much melanin during the winter months, but produce more when exposed to the sun. The melanin is diffused into the surrounding skin cells, called keratinocytes. The colour of ephelides is due to localised accumulation of melanin in keratinocytes.
Ephelides are more prominent in summer but fade considerably or disappear in winter as the keratinocytes are replaced by new cells.
As the person ages this type of freckle generally become less noticeable. Apart from sun protection, no particular treatment is necessary.
Lentigines are due to localised proliferation of melanocytes. The most common type, solar lentigines, arise in middle age and also result from sun damage (age spots). They are most often found on the face and hands, and are larger and more defined than freckles. Lentigines tend to persist for long periods and don't disappear in the winter (though they may fade). The correct term for a single lesion is solar or actinic lentigo.
Lentigines are common in those with fair skin but are also frequently seen in those who tan easily or have naturally dark skin.
It is important to distinguish the harmless solar lentigo from an early malignant melanoma, subtypes lentigo maligna and lentiginous melanoma. If the freckle has arisen recently, is made up of more than one colour or has irregular borders or if you have any doubts, see your dermatologist for advice. It is sometimes difficult to tell a benign lentigo from a melanoma, particular if there are atypical features clinically or pathologically. This is called atypical melanocytic hyperplasia. Such lesions should be completely removed by surgical excision with pathological examination.
If the brown marks are scaly, they may be actinic keratoses (sun damage) or seborrhoeic keratoses (senile warts). In this case there is a proliferation of keratinocytes. Facial pigmentation may also be due to melasma, a chronic pigmentatary disorder.
Not all brown marks can be prevented. Careful sun protection will reduce the number of new solar lentigines. Staying out of the sun and using sun protective clothing is much more effective than sunscreens alone. Sunscreens must have high sun protection factor (SPF 50+), good broad spectrum cover against ultraviolet radiation (UVA), and should be applied liberally and frequently.
Brown marks may fade with careful sun protection, broad spectrum sunscreen applied daily for 9 months of the year. Regular applications of anti-aging or fading creams may also help. These may contain hydroquinone, or antioxidants such as:
Suitable green-light devices include:
Suitable red light devices include:
Results are variable but sometimes very impressive with minimal risk of scarring.
With superficial resurfacing techniques, there is minimal discomfort and no down-time but several treatments are often necessary. Unfortunately the treatment occasionally makes the pigmentation worse. Continued careful sun protection is essential, because the pigmentation is likely to recur next summer.
If there is any doubt whether a brown mark may be a cancer, your doctor may choose to observe the lesion (e.g. with mole mapping or photography) or excise it for pathological examination.
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