Differential Diagnosis
The list of conditions being considered as possible explanations for your symptoms.
What it means
The list of conditions that could explain your symptoms, which testing then narrows down.
The important point: it is a list of things being ruled out, not a list of things suspected. Serious conditions appear on differentials routinely and precisely because they need excluding, not because anyone thinks you have one.
Seeing "cancer" or "MS" on a differential is alarming and usually means the opposite of what it looks like — it means someone is being thorough.
In practice
In clinic letters, referral letters and hospital notes, often as a short list after the presenting problem.
Increasingly read by patients before anyone explains it, which is where most of the distress comes from.
Why it matters
Ask which one is thought most likely, and what would move it up or down the list. That question turns a frightening list into a plan.
Ask what has already been excluded. Often the alarming item has been ruled out before the letter was even typed.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 30, 2026