Diagnosing lesions of the oral mucosa is necessary for the proper management of patients. Clinical differential diagnosis is the cognitive process of applying logic and knowledge, in a series of step-by-step decisions, to create a list of possible diagnoses. Differential diagnosis should be approached on the basis of exclusion. All lesions that cannot be excluded represent the initial differential diagnosis and are the basis for ordering tests and procedures to narrow the diagnosis. Guessing what the one best diagnosis is for an oral lesion can be dangerous for the patient because serious conditions can be overlooked.
It is helpful for clinicians to organize their knowledge of oral pathology using a system that simulates the clinical appearance of oral lesions. A decision tree is a flowchart that organizes information so that the user can make a series of step-by-step decisions and arrive at a logical conclusion (Figure 1).