Sebaceous nevus is primarily associated with localized epidermal growth and development, and is a type of benign hyperplasia. Most people are affected from birth or at a very young age, generally limited to one area and do not spread massively or contagiously across the body. Flat warts are caused by human papillomavirus (HPV) infections, which are contagious and recurrent, and can appear all over the body, not just in one area. Flat warts are generally dot-like or circular, whereas sebaceous nevi are mostly linear in growth, becoming larger and more proliferative over time. The most common treatment for sebaceous nevus is surgical removal, while flat warts can be selectively removed using laser treatment.