A 25-year-old man presents to dermatology with a “yeast infection” at the corners of his mouth that has failed to respond to anti-yeast creams (nystatin, clotrimazole) and oral medications (fluconazole). He has also tried a variety of “home remedies,” including hydrogen peroxide, rubbing alcohol, mouthwash, diaper cream, triple-antibiotic ointment, and tea tree oil. If anything, these seemed to worsen the problem.
He is fairly sure the problem developed because, several weeks ago, he shaved too close in the affected area. Soon after, he went to the dentist, who suggested the problem might be caused by a vitamin deficiency—but several weeks of taking a multivitamin produced no discernable result.
The affected area is irritated and sometimes painful, and he has a hard time leaving it alone. Several times a day, despite knowing how counterproductive it is, he finds himself picking at it. But worst of all, to the patient, is the fact that his girlfriend refuses to let him near her, citing fears of contagion.
The patient claims to be in good health otherwise, although his history includes seasonal allergies and eczema.
EXAMINATION
The corners of the patient’s mouth are quite macerated, eroded, and focally scaly, with modest erythema. There is no edema or tenderness on palpation. Examination of the inside of his mouth is within normal limits.
What is the diagnosis?