An 81-year-old man is brought in by his wife for evaluation of a very itchy rash on his bilateral lower tibial areas. He says the problem started about six months ago, after a spate of summer yardwork during which he sustained what he assumed was a bug bite. It was itchy, so he scratched it.
Of course, in the way of most itches, the scratching offered temporary relief, after which the itching resumed. The patient tried any number of OTC products, including rubbing alcohol, hydrogen peroxide, tea tree oil, several different essential oils, and triple-antibiotic cream and ointment. The worse the itching became, the more products he applied—all to no avail.
The patient describes his health as otherwise decent. He does have type 2 diabetes, which he says is in good control.
EXAMINATION
The lower anterior tibial areas of both legs are covered by a scaly red rash. The left leg is more heavily affected, and obvious edema can be seen distal to the rash on that leg. The surface scales of the rash have a polygonal look, resembling a dried lake bed or finely cracked porcelain. The edges of the cracks turn upward, resulting in a rough feel on palpation.
The patient’s skin is quite dry in general but otherwise within normal limits.
What is the diagnosis?