A glomus tumor is a benign (harmless) tumor of the nail bed. Its hallmark is pain and tenderness (sometimes in response to pressure and cold) or spontaneous pain. It often appears as a small red or pink area under the nail plate, but sometimes it is difficult to see. Glomus tumors are composed of blood vessels, which is why they appear red. The treatment for a glomus tumor is surgical removal. This treatment has a good outcome and the nail usually grows back without any permanent damage. (supplied by Phoebe Rich, MD)