DefinitionSkin lumps are any abnormal lump or swelling on the skin.ConsiderationsMany people wonder if small bumps or lumps on the body are something to worry about. Most lumps and swellings are benign (not cancerous) and are harmless, especially the kind that feel soft and roll easily (lipomas).A lump or swelling that appears suddenly (over 24 - 48 hours) and is painful is usually caused by an injury or an infection.Common CausesLipomas, fatty lumps under the skinEnlarged lymph glands, usually in the armpits, neck, and groinCyst, a closed sac in or under the skin that is lined with skin tissue and contains fluid or semisolid materialBoils, painful, red bumps usually involving a hair follicleCorn or callus, caused by skin thickening in response to continued pressure (for example, from shoe