It is a discolouration and/or palor of the skin that is left on the skin after an underlying skin disease has healed. The underlying skin disease may be trauma, skin infection, eczema or a drug reaction. This tends to improve with time.  In dark-skinned persons, the dyspigmentation tends to be more intense and persists for a longer period.

Freckles are light brown small flat spots <1cm that appear on areas of sun exposed skin such as the cheeks and nose. They are usually present at a young age and tend to increase with age. Solar lentigenes are brown spots 1 cm or greater in diameter, occurring usually on the face and back of the hands. Solar lentigenes are evidence of excessive sunlight exposure. They are found in individuals over 40 years of age, especially if they have a long history of sun exposure.

Melasma is a common pigmentary problem affecting the Asian skin, it usually appears as brownish patches over the cheeks although the forehead, temples, nasal bridge, upper lips and jawline may be affected as well. Melasma results from the interplay of genetic, hormonal and UV factors. Women are more commonly affected compared to men. Worsening is often reported after sun exposure, pregnancy and the use of oral contraceptives.

Pityriasis alba is a common skin complaint of children and young adults. It appears as pink scaly patches which later leave pale areas on the skin. These pale areas are more noticeable in people with dark skin, and more pronounced after exposure to the sun and the tanning of the non-affected skin. The cause is unknown. It is thought to be due to a minor form of inflammation in the skin, related to eczema.

Certain medications such as minocycline, hydroxychloroquine, hydroquinone and amiodarone can cause hyperpigmentation of the skin ranging from slate grey to blue-black discolourations.

Vitiligo is a skin disorder which presents as white spots and patches on the skin. This is due to a progressive loss of pigment cells (melanocytes). Vitiligo is not contagious. Vitiligo is considered to be an 'autoimmune' condition in which the body's own immune system rejects some of its own cells (melanocytes in the case of vitiligo). As a result, thyroid disease and other autoimmune conditions are more common in individuals with vitiligo. Repeated trauma such as rubbing or scratching the skin may trigger and aggravate vitiligo.

Usually, normal skin colour will return slowly over a period of months. One should avoid further trauma to the area, e.g. frequent rubbing and sunlight exposure. In hyperpigmentation, bleaching agents such as those containing hydroquinone may be used. Occasionally a mild steroid may help.

Freckles and lentigines can be reduced and lightened by avoiding sun exposure and with the regular use of sunscreens and skin lightening creams. If creams and sun avoidance still do not give satisfactory results, they can be safely removed with intense pulsed light therapy or pigment laser treatment. Most patients will require about four to six treatment sessions to obtain optimal results.

Melasma is challenging to treat as recurrence after initial successful treatment is high. Melasma is best controlled with the regular use of broad spectrum sunscreens, sun avoidance and lightening creams. Prescription-only combination creams may offer rapid initial clearance of the melasma. For difficult cases, chemical peeling, intense pulsed light therapy, oral tranexamic acid and laser treatments may offer additional benefits but the results are variable.

Medical treatment is not needed unless the skin is uncomfortable from itching. The dryness can be helped by using a moisturiser and avoiding soap. If the patches are red or itchy, a mild steroid cream (hydrocortisone) can be applied for a short period to improve symptoms. Sunscreens in summer may prevent the patches becoming more noticeable by reducing the tanning of the non-affected skin.

Skin lightening creams are usually first line treatment. The offending drug must also be discontinued if possible. Difficult cases may be treated with pigment lasers but results and variable.

Sunscreens: Areas of vitiligo will burn easily in the sun. The use of a sunscreen with a high sun protection factor (SPF) of 30 or higher to all exposed areas helps to protect skin affected by vitiligo.

Topical corticosteroids:  The application of a potent or very potent corticosteroid anti-inflammatory cream or ointment to areas of vitiligo may restore some pigment. Side effects, such as thinning of the skin and stretch marks, are a risk with continued use. Short courses of oral steroids can sometimes be considered but may be associated with side effects such as weight gain, skin thinning, mood changes and cataracts.

Other topical preparations: Other types of anti-inflammatory creams and ointments, such as calcineurin inhibitors and vitamin D analogues, may also restore pigment in some patients. These topical treatments will help avoid the corticosteroid side effect of skin thinning.

Phototherapy: This involves exposing affected skin to artificial ultraviolet light. Phototherapy may be helpful in a proportion of patients with vitiligo. However, treatment often needs to be prolonged (lasting at least several months). Phototherapy may be used in combination with topical or oral corticosteroid treatments.

Laser treatment: Some areas of vitiligo have improved from treatment with a laser called the Excimer laser. Laser treatment can be used in combination with topical treatments