hyperpigmentation....so you dont have to read if you dont know about it...( :

This is all I know:

Hyperpigmentation means an excess of pigment. There are several types of hyperpigmentation seen in humans:
- freckles
- disease-related hyperpigmentation
- pregnancy-related hyperpigmentation
- enzymatic deficiencies

Freckles are areas where the melanocytes (pigment-making cells) are more active and responsive to UV radiation than in neighboring skin. Freckles tend to be more pronounced in childhood. They are associated with fair hair and skin.

Hyperpigmentation is seen in cases of hyperpituitarism and Addison's disease.

Hyperpigmentation is also sometimes seen in mothers during pregnancy. The increased pigmentation seen in pregnancy is due to the influence of estrogen, progesterone, and melanocyte-stimulating hormone. Hormonally related hyperpigmentation, such as that occurring in pregnancy, can also show up as a condition called the mask of pregnancy, or melasma. This is a condition in which blotches of pigmentation appear on the face or in sun-exposed areas. Melasma is harmless. The pigment seen in melasma usually goes away within several months of delivery. However, skin lighteners (such as hydroquinone or tretonin) are sometimes used to treat the condition.

Some people may have a deficiency in the liver enzyme that metabolizes carotenes. People with this deficiency who eat large quantities of carrots, peppers, or other yellow/orange vegetables may find that their skin color changes. In particular, their skin may become tinged with yellow or orange pigment.