Welcome to the forum chaitanya, your condition looks like Becker melanosis to me which is harmless condition. Treatment is only for cosmetic reason which can be achieved with lasers.
I have this weird problem... Since 2-3 years I have noticed that their are black spots on my upper left arm but i have ignored it since then,,, But recently after reading an article about skin problems I got really worried and wanted to know what those patches are... I am attaching some pics.. I would appreciate if someone could help me... And one more thing black hair are growing out of those patches..IMG_20140619_084628.jpg
Welcome to the forum chaitanya, your condition looks like Becker melanosis to me which is harmless condition. Treatment is only for cosmetic reason which can be achieved with lasers.
It seems that it will not go away. You should see your skin specialist and go through the treatment for it.
There are various treatments, you should consult with a surgeon. A surgeon can suggest you best treatment although a laser treatment or any other. Without seeing nobody can suggest.