Fluid-filled sacs
Typically painless
Slow-growing
They can feel firm or slightly movable under the skin.
Most are harmless, but it’s still worth having them checked if they persist or grow.
4. An Insect Bite or Sting Reaction
Certain insect bites can cause unusual skin reactions that look more serious than they are.
You might see:
Swelling
A central mark or puncture
Redness or itching
In some cases, the reaction can make it seem like something is embedded in the skin.
5. A Skin Infection
If bacteria enter through a small cut or puncture, it can lead to a localized infection.
One example is Cellulitis, which causes:
Redness
Warmth
Swelling
Pain
Another possibility is a small abscess—a pocket of pus that can feel like a lump under the skin.
These conditions require medical attention, especially if symptoms worsen.
6. A Vaccination or Injection Site Reaction
