A 58-year-old man asks about this painless lesion on his left third digit. It does not itch, burn, or sting and there are no other similar lesions. He had a history of basal cell carcinoma on the arm and several more recent actinic keratoses on his scalp. What’s your diagnosis?
Allergic contact dermatitis, drug-induced hypersensitivity syndrome, Stevens-Johnson syndrome, metastases to the skin, tinea versicolor, lichen spinulosus—a look at cutaneous conditions and their underlying causes.