Münchausen syndrome is a mental illness where sufferers fake symptoms and actively seek out serious medical care. It is extremely difficult to diagnose as sufferers make themselves extremely knowledgeable about medical procedures and move from doctor to doctor when under suspicion. Often a doctor will correctly identify a patient, refer them for psychiatric care, and then have the patient move on to another unsuspecting doctor.
The disease is named after Baron Münchhausen, a German aristocrat who was infamous for his tall tales.