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Five progressive clues
These are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 72-year-old man books an urgent visit with his dentist because both corners of his mouth have become painfully cracked and sore over the past few weeks. He is embarrassed and anxious to have it cleared up before his granddaughter's wedding, and admits he has been dabbing petroleum jelly on the spots for a fortnight with no improvement.
Clue 2
The soreness is symmetrical, affecting both angles equally, and is worst first thing in the morning and whenever he opens wide to eat. The skin feels tight, then splits and stings; he catches himself licking the corners for relief. He has worn the same upper complete denture for about 12 years and has never had it relined. He reports no blisters or tingling elsewhere on the lips, and no rash on the rest of the face.
Clue 3
Examination shows the lower third of his face looks foreshortened, with deep creases folding inward at both mouth corners; his denture teeth are worn nearly flat. The redness, maceration and fissuring are sharply confined to the commissures and do not extend onto the red border of the lips. There are no vesicles, no crusted vermilion lesions, and no ulceration of the lip proper.
Clue 4
A swab taken from the fissured corners is cultured and grows Candida albicans. A blood panel ordered to exclude a systemic cause returns normal serum iron, ferritin, folate and vitamin B12. Intraorally, the mucosa of the hard palate seated beneath the upper denture is diffusely reddened in the exact outline of the denture base.
Diagnosis
Angular Cheilitis
Why the diagnosis fits
The inflammation is confined strictly to both oral commissures, not the vermilion body or lower lip, and arises where a decade-old worn denture has reduced occlusal vertical dimension, deepening the melolabial folds so saliva pools and macerates the skin, with secondary Candida overgrowth (confirmed on swab and by the coexisting denture-bearing palatal erythema). The single key discriminator from recurrent herpes labialis is the distribution and morphology: bilateral, chronic, non-vesicular fissuring limited to the angles that heals only when vertical dimension is restored and the yeast treated, versus a unilateral, self-limited vesicular crop on the vermilion. Normal hematinics exclude a nutritional driver, and the commissure-only pattern excludes sun-driven lower-lip disease.
Educational reference
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Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.