Luckily, bumps on the back under the skin are actually quite common and they are usually not a serious medical problem. That being said, if the bump grows rapidly or if you start to notice other bumps in other places, or if the bump becomes red and inflamed, you should have it checked out by your primary care doctor
. Similarly, any unexplained fever, loss of appetite, or weight loss
should also be checked out by your doctor.
One likely possibility is that this is a lipoma. Lipomas are benign tumors of fatty cells that are more common as we age. The appear soft and fleshy and usually move easily under the skin. Lipomas are not serious and do not need treatment. However, sometimes they can continue to grow and become uncomfortable or unsightly, in which case you can talk to a surgeon
about taking it out.
Another possibility is a sebaceous cyst, which is a collection of thick cheeselike material under the skin. Often these cysts have a pore and will sometimes leak fluid out and will occasionally become inflamed. Again, these are not dangerous but are often removed because they become infected or uncomfortable.
Talk to your primary care doctor if you have any more questions.