10 Facts About Lipomas 1. A lipoma is a benign (non-cancerous) tumour made of fat cells. It grows slowly and is not harmful in the majority of cases. 2. They are the most common soft-tissue tumour in adults. Many people develop at least one in their lifetime. 3. Lipomas usually form just under the skin, commonly on the neck, shoulders, back, arms, thighs, or torso. 4. They feel soft, rubbery, and can be moved easily under the skin because they are not attached to deeper structures. 5. Most lipom