A Brownish Skin Lesion on the Upper Neck

A 20-year-old man presented with a 2–3-cm brownish skin lesion on his left submandibular neck. He has been playing violin since he was five years old. He is studying music and nowadays, his rehearsing has increased to at least five hours a day. The lesion has gotten thicker and darker over the past few months but he has sought no medical treatment yet.