Differential diagnosis
Use the pattern of symptoms, examination and investigations to keep serious alternatives in view. Revisit the differential when findings conflict.
Understand
A differential is a ranked set of explanations that accounts for the findings and serious alternatives. Prevalence helps, but red flags and discordant evidence can outweigh it.
Assess
For each leading diagnosis, identify confirming and excluding findings and the investigation that would change management. Think beyond odontogenic disease for facial pain, swelling and ulceration.
Apply
Reassess when the expected course fails. Safety-net explicitly: what change should prompt urgent contact, who will review a result and by when.
Key distinctions
Rank alternatives by likelihood and consequence. A common benign cause may be most likely, while a less likely malignancy still needs exclusion because missing it carries greater harm. State what finding would falsify the leading diagnosis and set a review interval that is shorter than the time in which a serious condition could be missed.
Think through a case
A presumed traumatic ulcer remains after removing a sharp cusp. The failure to heal contradicts the working diagnosis and should trigger a new assessment and referral decision.
The distinction to remember
Do not repeatedly defend an initial diagnosis when the clinical course supplies contrary evidence.
Test your recall
What should happen when a presumed benign lesion persists or changes?
Show answer
Reassess and arrange appropriate investigation or referral.