There is a round thing on the neck, this situation may be localized formation of fibroma. The formation of this fibroma specific reason is difficult to say, generally there may be trauma and the formation of a proliferative reaction, there may be mosquito bites and other formation of fibrosis hyperplasia. There is no obvious health risk to the human body, but there may also be a viral infection and the formation of wart-like growths. For example, molluscum contagiosum caused by molluscum contagiosum virus infection. It is also possible that the area is infected with human papilloma virus and the formation of flat warts, which will also produce a certain wart-like growth, but the surface is flat and smooth, most of them do not have obvious self-conscious symptoms.