Hi I am a boy my neck and face coming dark spot...

Treatment for darker neck and face: 
Treatment is done by treating the cause that leads to the occurrence of these symptoms, after conducting the necessary medical examinations and arriving at an accurate diagnosis. The cause and treatment are determined by the doctor. 
The treatment may be done by using topical creams that contain salicylic acid and Retin-A, and alpha hydroxy acids, in addition to oral medications and natural products or masks to help Unification of skin color. 
Diagnosis:
Diagnosis is made by taking a detailed medical history, family history, clinical medical examination of the patient. Also some test should be carried like CBC and blood sugar analysis to exclude having diabetes. Also x-ray and may be done.
Symptoms:
*Itching
*Thickend skin
*Velvety skin texture
Advice:
You should apply skin protection against UV radiation of the sun and consult the dermatologist.