When something on your body worries you, take heart. Most lumps that appear on the skin are common, well understood and can be dealt with calmly.
This photo shows a woman’s upper back from behind, with a large red swelling just below the shoulder and a few smaller bumps scattered around it.
A lump like this is most likely an epidermoid cyst. It starts when a hair follicle on the back becomes blocked and a small sac forms under the skin.
The back has many oil glands and is hard to wash thoroughly, so blocked pores are common there, and the smaller bumps around it are often early blockages.
Over months the sac slowly fills with keratin and grows. When it becomes inflamed, it turns red, feels warm and tender, and a whitish head may appear at the top.
