It is a discolouration 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.
In dark-skinned persons, the colour tends to be more intense and persists for a longer period.
The pigmentation tends to clear with time.
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.