These 20 Strange Symptoms Can Signal a Serious Disease

So often your lumps, bumps, rashes, and red spots are harmless. Occasionally, they’re a sign of something far more serious. 

Your neck looks dirty

A rash-like discoloration called acanthosis nigricans “almost looks like dirt but has a velvety feel,” says Todd Jeremy Sontag, DO, a family medicine specialist with Orlando Health Physician Associates in Orlando, Florida.

He commonly sees it on the back of the neck or in the armpit. This is often a sign of diabetes or insulin resistance. “Patients will come in asking about this rash they can’t get rid of,” he notes. A doctor will order blood tests to check blood sugar levels to make the diagnosis.