Creutzfeldt–Jakob disease
Biopsy: To do a biopsy, a doctor uses a needle to take a small piece of tissue from the body, so doctors can look at it under a microscope.  vCJD can be diagnosed with a biopsy of the tonsils.  For all of the other types of CJD, a biopsy of the brain is the only way to tell for sure if a person has CJD.  However, since a biopsy of the brain can cause brain damage, a brain biopsy is usually not done if other tests have already shown that a person probably has CJD.