Hyperpigmentation

THE FUNCTION OF MELANIN

Skin color is determined by the amount of pigment or melanin that an individual produces. Melanin is manufactured by the melanocyte cells which are found through out the basal cell layer of the skin. Skin color is formed via a complex process having to do with the interaction of an amino acid known as tyrosine. A hormone released by the pituitary gland is the primary factor in what controls the amount of melanin and the appearance of overall skin color.

There are only two aspects of pigmentation that differ among persons of various skin colors. First, in lighter skinned individuals the melanozomes (the granules within the melanocytes cells) are smaller than in the skin of individuals in the darker ranges. Secondly, in darker skinned persons the melanocytes are more active and produce more melanin.

It has been confirmed that pigment plays a role in protecting the skin from damage caused by ultraviolet light (sun exposure). recent studies indicate that this protective action is due to melanin's ability to act as a potent free radical scavenger. Apparently, free radicals that are triggered through sun exposure are neu tralized by melanin which in turn aids in preventing cellular DNA damage.

ABNORMAL PIGMENTATION

Hyperpigmentation is defined as any abnor mal increase in genetically programmed skin pigmentation.

There are many factors that may contribute to changes in skin color or uneven pig mented patches. These include:

UV light
Chemical (industrial chemicals or chemical peeling agents)
Local infection
Hormones
Drugs
Acne

Skin diseases and inherited genetic abnormali ties can also be causes of overpigmentated areas. Common hyper-pigmentation com plaints are usually focused on freckles, solar lentigo (areas of discoloration from sun exposure), flat macule discoloration (from acne), melasma and post inflammatory discoloration. The following is a brief discussion of each of these disorders:

Freckles. Freckles are tan to pale brown spots with poorly defined borders. Indi viduals with freckles appear to have no greater number of melanocytes in the freck led areas as there are in non-freckled areas. However, freckled areas react to ultraviolet light by increasing the production of pigment. Freckles are usually apparent on fairer skinned individuals and are more prominent in summer months during increased sun exposure. (Fig. 1)

(fig.1)

Solar Lentigo. Solar Lentigos are areas of brown pigmentation that appear only after intense short term sun exposure or ongo ing cumulative sun exposure. This form of hyperpigmentation involves an increase in the number of melanocytes. Generally the areas most affected are the face and the back of the hands. (Fig. 2)

(fig.2)

Melasma. Melasma is characterized by blotchy brown hyperpigmented patches that have an irregular shape and may be distributed over the cheeks, forehead, up per lip and neck. Frequently, this condition occurs during pregnancy, at menopause and in those taking hormones or oral contra ceptives. It can also rarely occur in men. Sun exposure and certain topical or oral medications can worsen the appearance of the discolored areas dramatically.

Melasma can affect either the epidermal (su perficial) layers of the skin or the dermal layers (deep) or consist of a combination of both. A Woods lamp can be used to dif ferentiate which level of pigmentation the patient is experiencing. Epidermal pigmen tation will appear accentuated under a

Woods lamp, whereas dermal pigmenta tion will disappear or become less obvious. It is important to make this distinction be cause epidermal pigmentation may respond well to being lessened or resolved with topical agents while dermal pigmen tation may need to be addressed more aggressively. (Fig 3)

(fig.3)

Post Inflammatory Discoloration (from chemical peel agents). Aggressive chemi cal peel agents such as TCA, phenol or non-neutralized glycolic acid may produce complications resulting in uneven colora tion. This form of hyperpigmentation may leave a large area or small areas of discol oration with irregular shapes ranging from blotches to streaks or whorls. (Fig. 4)

(fig.4)

Postinflammatory hyperpigmentation is most common in olive or darker skinned individuals. It can occur in fair skinned patients, although it usually lasts a shorter period of time.

Even though patients may be patch tested and screened for pigmentation tendencies, problems can occur even if precautions are observed. This is because pigmentation is a normal response to the intended irritation/wounding of stronger peeling agents. This causes the melanocytes to become hypersensitive. The hypersensitiv ity can last for months, which is why it is critical to maintain consistent use of a to tal sunscreen and also avoid sun exposure. Most individuals have greater sun exposure to UV rays than they realize because even fluorescent office lighting can be a source of UV light.

A key factor as to whether or not the hyperpigmentation can be successfully resolved is immediate treatment. The interval between the appearance of pigmen tation and the start of treatment is often the determining factor as to a desirable outcome.

NON-PRESCRIPTION PRODUCT RECOMMENDATIONS

Glycolic Acid

Medical studies indicate that glycolic acid assists in resolving hyperpigmentation and encouraging an overall more even skin tone. It is believed that glycolic acid pro duces these changes by breaking down the cellular bonds of the dead layers (stratum corneum), causing a lifting of over pig

mented areas. Glycolic acid also has been shown to act as a delivery agent for other topical medications such as retina" and hydroquinone, thus enhancing the effects of lightening agents.

Kojic Acid
(Lightening Gel combination kojic acid and glycolic acid).

Kojic acid has been receiving attention medically and cosmetically as a new pig ment lightening agent. Kojic acid has been used safely in Japan for many years with out irritations or long-term complications that may be associated with other lightening medications.

Studies indicate that kojic acid is more effective than hydroquinone with results beginning to be noticeable within the first one to two weeks of application. When kojic acid is combined with glycolic acid, the effects appear to be magnified.

Azelaic Acid

Medical reports confirm that azelaic acid (Heptadicarboxylic acid or AA) is a potent component in the treatment of some hyperpigmentary disorders, such as melasma, chloasma and post-inflammatory hyperpigmentation. While the exact basis for its mode of action is still unknown it has been shown to be safe and non-toxic on humans for both short and long term use.

When azelaic acid is combined with spe cially balanced combinations of glycolic acid and salicylic acid, the action appears to be greatly enhanced and may be an ap propriate choice for some forms of hyperpigmentation.