There are several types of penis lumps with various causes that are normal and do not usually require medical treatment.Pearly penile papules,fordyce spots(yellow white in color),Lymphocele may occur when the lymph channels in the penis become blocked,A crop of purple or red bumps in an itchy rash, known as lichen planus, can affect the penis. sexually transmitted conditions are-Genital warts,syphilis,herpes,molluscum contageosum require treatment to prevent spread onto other individuals. A rare condition Peyronie’s disease also lumps are seen on penis. Penile cancer is a rare cause of lumps in the penis and requires treatment so should be detected as early as possible. To determine what exactly it is physical examination is required so you better take him to a qualified physician and get examined to know whether it is self limiting or requires treatment.