i have the same white hard lump in my scrotum. it had been here for almost 5 years. until it becomes i think about 1mm in diameter.
until i decided to cut it and to my amazement, it was really hard like a peeble, white and hard. i just pressed the skin to prevent feeling the pain when cutting, then i pushed outside the white hard substance using the tip of the knife. it sticked to the skin. it was removed whole and when cracked was powdery like limestone. whatever that was, i was relieved it was removed, and my scrotum is now free of that lump.