Hello, I can understand your concern for white spot on the penis due to leucoderma. It appears from your query that you have progressive Vitiligo on penis and is now increasing in size. Leucoderma or white skin disease is and skin problem where the color giving cells are damaged and are not able to manufacture color to the skin. The resulting situation is manifested as slight diminished pigmentation and finally progresses to complete white skin problem. There are multiple types of oral and topical treatments or combination treatment available to take care of the problem. The treatment should only be started by and skilled dermatologist. You must have good patience of multiple of months to see the visible results. In my patients I suggest to treat it with tacrolimus ointment or by mild oral steroid. I do nt prefer to give any oral treatment in most my cases. All the best