Diffuse erythematous rash resistant to treatment.

A 39-year-old woman presented to the emergency department for evaluation of diffuse redness, itching, and tenderness of her skin. The patient said the eruption began 4 months earlier as localized plaques on her scalp, elbows, and beneath both breasts. Over the course of a few days, the redness became more diffuse, affecting most of her body. She also noticed swelling and skin desquamation on her lower extremities. WHAT IS YOUR DIAGNOSIS? HOW WOULD YOU TREAT THIS PATIENT?