Lipoma
Lipomas are soft, fatty lumps that grow under your skin. They're harmless and don't usually need any treatment.
Check if you have a lipoma
Lipomas are common. They:
feel soft and squishy
can be anything from the size of a pea to a few centimetres across
may move slightly under your skin if you press them
aren't usually painful
often appear on your shoulders, chest, arms, back, bottom or thighs
grow slowly