Yellow bumps or patches on the eyelids, joints, trunk, or heels can be a warning sign of very high blood fat — bad news if ignored, but useful early notice for anyone who catches it.

• Yellow deposits form when cholesterol builds up so much it spills out of the blood and settles in skin and tendons.
• Four common types show up: flat patches on the eyelids, soft lumps on elbows, knees and knuckles, sudden rash-like bumps on the trunk and back, and thickened Achilles or finger tendons.
• The sudden rash-like type often means extremely high triglycerides and a real risk of acute pancreatitis, which can kill.
• Thickened tendons are close to proof of inherited high cholesterol, where heart attacks often strike in a person's thirties or forties.
• Clean skin means nothing: over 90% of people with high blood fat show no signs at all until a heart attack.

Outlook: Anyone spotting these growths should get a blood test rather than treat them as a cosmetic problem, and regular blood work stays the only reliable way to catch the risk early.