What does 'diagnosis of exclusion' mean?

Look for other first: Typically, "a diagnosis of exclusion" refers to an ailment diagnosed if nothing else fits. Perhaps there are no tests for that problem, or it would be a mistake to jump to a conclusion without evaluation. Example: chest pain can be a symptom of a panic attack, but if not obviously so, needs to be a diagnosis of exclusion since a heart attack or pulmonary embolus can also cause chest pain.