Human skin color varies from different hues of brown to pink. The pigment which determines the skin color of each individual is called as melanin. The skin color evolved primarily to protect the skin from the harmful UV rays. People who live near equator with high exposure to UV rays have more melanin pigments for protection. Hence they are dark skinned. People who live closer to the poles with less UV exposure have less melanin pigments and are light skinned.

Change in skin color can happen due to various reasons. Changes in skin tone because of tanning or scars are considered normal. Other changes which require medical advice are considered as skin abnormality.

Tanning

Tanning is caused when the skin is exposed to excessive sun rays. The body tends to produce more melanin for UV protection. The area exposed to sun rays becomes darker than the rest of the body results in uneven skin tone. Tanning is not exactly a skin condition or abnormality. Covering the exposed areas or using a sunscreen can protect one from the UV rays. But overexposure to UV rays can cause sun burns, skin ageing and even skin cancer.

Scars

Scars are a form of tissues called fibrous which replaces the normal skin after an injury.  Simple scars from small wounds, acne, itchy insect bites can fade away in weeks. Any other major wound or surgery can cause permanent scars. Even though the skin looks different from the rest of the body, scarring is considered as a natural part of the healing process. There are some treatments available as well to remove the scars.

Hyper pigmentation 

Hyper pigmentation is caused because of the over production of melanin but it is not only because of the exposure to UV rays.  Hyper pigmentation can be because of the various following reasons. Pregnancy can be one of the main reasons for hyper pigmentation. The skin is darkened around neck and at the lower part of stomach which eventually goes away after the child birth. Decrease in the function of adrenal gland can cause hyper pigmentation.  Use of certain medication is one of the reasons for hyper pigmentation.  Skin inflammation, fungal infection, accumulation of iron in the body, exposure to mercury and smoking are the other reasons for hyper pigmentation.

Acanthosis Nigricans

Acanthosis Nigricans is a type of hyper pigmentation caused by hormonal imbalance. It results in occurrence of dark patches on neck, under arms and knuckles. The dark patch is nothing but extra skin cells produced by the imbalanced hormones regulating the blood sugar level called insulin. Sedentary lifestyle, junk food, lack of exercise, obesity, diabetics and polycystic ovary syndrome are the causes of Acanthosis Nigricans.

These dark parches are often mistaken as dirt accumulation. Irrespective of regular cleaning and scrubbing, these patches won’t fade away. Doctor consultation is a must to treat this condition. Proper medication along with healthy food and lifestyle changes can help to overcome the condition.