Derm Dx: Itchy red plaques and blisters

A 75-year-old woman presents with extremely itchy red plaques on her trunk and extremities, which she reports were present for months. Initially the eruption started on her shins, but subsequently generalized. Her face and genitals are spared, and she denies any blisters or erosions in her mouth. Symptom review is otherwise negative.

The patient has a history of hypothyroidism for ...