For more than 2 years, this 36-year-old woman has had a slightly itchy rash that waxes and wanes on her posterior neck. She has consulted several primary care providers and received multiple diagnoses, the most consistent of which has been fungal infection. However, despite use of a variety of antifungal creams (nystatin, clotrimazole, and combination clotrimazole/betamethasone), a 1-month course of oral terbinafine, and OTC tolnaftate, no improvement has occurred.
The patient asserts that she is otherwise in good health, with no joint pain or fever and no history of recent health crises. Family history is free of dermatologic complaints except for psoriasis in her father.
A pink plaque with white, fairly adherent scale covers most of the patient’s posterior neck/upper midline back. When a 3-mm section of scaling is peeled away, 2 tiny dots of pinpoint bleeding are immediately noted.
The rest of her scalp is free of any such changes, as are her elbows and knees. But a similar rash is seen in the upper intergluteal area, and 3 of 10 fingernails are mildly pitted.
What’s the diagnosis?