Healing rarely happens in a hurry. Steady as you go is a good rule for most things in life, and it is a very good rule for skin problems.
This photo shows a man in his 50s sitting on an exam table, with a round, golf-ball-sized swelling on his shoulder blade. The skin over it is red and stretched, with a small yellowish head off to one side.
A lump like this is most often a sebaceous or epidermoid cyst. It forms when a follicle on the shoulder becomes blocked and keratin slowly builds up under the skin.
The shoulders and upper back carry a lot of friction from shirts, seat belts and straps, and they are hard to see and clean, so cysts there often grow unnoticed for a long time.
As the cyst enlarges it becomes firm and tender, and the surrounding skin turns red. Moving the arm, sleeping on that side or wearing a heavy jacket can all become uncomfortable.
