There are many reasons of having darker patches on facial skin. See also brown spot/age spots.
Post Inflammatory Pigmentation
The pigmentation can be a result of injury or inflammation to the skin. This is called post inflammatory pigmentation. It could be due to a skin disorder such as eczema, psoriasis or lichen planus pigmentosus. In addition, it could be due to trauma, treatments such as cryotherapy or surgery. Darker skin types can more susceptible to this type of pigmentation. If the pigmentation is superficial layer of the skin, then it could response to lightening agents such as Obagi and chemical peels. Avoidance of sun is a good idea to prevent worsening of pigmentation. If the pigmentation is deeper in the skin, then it would be difficult to remove or reduce.
This is a common pigmentory disorder seen as irregular patches of cheeks in females. It can affect other areas of the face and rarely seen in sun exposed areas of the body. There is hormonal influence and Melasma is most commonly starts during pregnancy or due to contraceptive use. Sun and heat (infrared) exposure is a major aggravating factors and should be strictly avoided where possible. This condition is very difficult to treats, options are topical lightening agents, chemical peels and lasers.
Solar Lentigo is a flat round or oval shaped uniform-coloured brown spot often seen in sun exposed area of the skin. They are often multiple, some larger and some smaller. They are caused by chronic sun exposure, and therefore, the cheeks and back of the hands are the most common areas to have these. They do not usually cause any itchy or pain or bleeding. If these symptoms occur, it is best to consult a doctor. Many treatments are available including topical lightening agents, cryotherapy, chemical peels and lasers.
This is sometimes mistaken to be solar lentigo of the cheeks. They are most commonly seen in young to middle aged East Asian females. There are multiple small brown to grey to greyish brown round or oval flat spots of cheeks. The pigmentation is deep in the skin and therefore do not response to topical treatment creams. This condition is best treated with a laser.