The cause of a sudden mole on the hand is not very clear. It may be related to factors such as UV exposure, age, gender, race and skin color.
Pigmented nevi are formed by abnormal aggregation of melanocytes. Ultraviolet light exposure may lead to an increase in pigmented nevi, so try to avoid exposure to ultraviolet light.
Pigmented nevi may be related to age. Naevus pigmentosus may appear in childhood and gradually increase in number, reaching a peak in puberty and decreasing in middle age and old age.
Nevus pigmentosus is also related to gender. Usually, women are more likely to develop moles than men.
Moles may also be related to race and skin color. Lighter-skinned people are usually more likely to develop moles than darker-skinned people.
If a pigmented mole suddenly appears on your hand, you can visit a hospital dermatologist.