While the oral ulcers are identical, Behcet's is a systemic vasculitis distinguished by the presence of concurrent genital ulcers and eye inflammation (uveitis).
Ulcers from chemotherapy (mucositits) are distinguished by a clear history of drug administration and are often more widespread and diffuse than discrete aphthous ulcers.
Oral DLE lesions are typically painless, atrophic, white plaques with surrounding erythema, often on the palate, unlike the painful, punched-out ulcers of aphthous stomatitis.
This is identified by the recurrent appearance of a single or few ulcers in the exact same spot each time a specific drug is taken.
Herpetic ulcers are distinguished by their preceding vesicular stage and their classic location on keratinized mucosa (hard palate, gingiva), whereas aphthous ulcers favor non-keratinized mucosa (cheeks, tongue).
Erosive lichen planus can cause painful ulcers, but it is distinguished by the presence of surrounding white, lacy (reticular) striations (Wickham's striae).
This autoimmune blistering disease causes large, persistent, and scarring erosions, particularly of the gingiva ("desquamative gingivitis"), a more severe presentation than recurrent aphthous ulcers.
Ulcers in neutropenia are often large, deep, and necrotic ("agranulocytic angina") and are defined by a concurrent low neutrophil count on a blood test.
Pemphigus vulgaris typically begins with extensive, painful, and fragile oral erosions that precede skin blisters, a much more severe and widespread presentation than common aphthous ulcers.
An ulcer that is persistent, non-healing for weeks, and develops firm, indurated borders should raise suspicion for SCC over a transient aphthous ulcer.
This is an acute, severe mucocutaneous reaction, distinguished by widespread, hemorrhagic crusting of the lips and extensive sloughing, far beyond a few discrete ulcers.
A primary syphilitic chancre is typically a single, painless ulcer with a firm, indurated base, while secondary syphilis causes mucous patches, which are painless, greyish-white plaques.
