CASE
A 39-year-old man complained of a lesion on his right thumb that had persisted for more than 6 years despite treatments that included liquid nitrogen, OTC wart remedies, topical corticosteroid cream, and intralesional injection of corticosteroids. Previous health care providers, including dermatologists, had diagnosed wart, corn, callus, and possible foreign body. A radiograph obtained several years previously had provided no diagnostic clues.
The lesion had begun as a slight rash that was confined to the dorsal surface of the thumb and itched constantly, causing the patient to scratch often. Over time, the rash became lesional, taking on increasing depth, width, and firmness, eventually attaining its current size, and continuing to itch. The patient had suffered from seasonal allergies, asthma, and eczema since he was a child.
On examination, the lesion measured 5 cm long by up to 2 cm wide and was raised to a height of 4 to 5 mm above the skin (Figure 1). Compared with the patient's dark, type IV, Native American skin, the lesion was relatively depigmented and quite firm to the touch. Except for being quite dry, the rest of his skin was unremarkable.
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