An itchy rash with multi-regional crusts and scalp erosion

A woman in her 60s who was bedridden presented with a two month history of an itchy, scaly, widespread rash. She was known to have Raynaud’s syndrome and bullous pemphigoid, which was controlled with prednisone, doxycycline, and nicotinamide. Two months before this presentation, she had been admitted to hospital for lumbar osteoporosis, where she had been on a ward with a patient who had a pruritic rash. Two weeks after discharge, the woman had developed generalised urticarial papules and pruritus that was worse at night. She had used topical steroids to manage these symptoms, but saw no improvement. Her husband and daughter also had an itchy rash on the torso and hands. On examination, erythematous papules were scattered over the face, trunk, and limbs, while erythema and powdery yellow scales/crusts were distributed on the scalp, postauricular area, nipples, umbilicus, and finger webs, …