A 52-year-old woman presents with a six-month history of a pruritic rash. She states that itchy red spots and patches appear "out of nowhere", anywhere on her body, disappear within a couple of hours, then reappear in a different location. She may go without these spots and patches for a few days, but they reappear from time to time. She notes that the unpredictable nature of these spots causes her significant stress. Separately, she also describes occasional swelling of her lips and around her eyes. She denies any dizziness, dyspnea, nausea, and diarrhea. She denies exposure to new medications, new foods, or new skin products, and she denies recent upper respiratory tract infection and known allergies. She is not prescribed an ACE inhibitor or angiotensin receptor blocker. The only non-prescription medicine she takes is acetaminophen as needed. She has been given antihistamines and oral steroids which have provided some relief, but the condition persists. There is no history of fever, malaise, joint pain, or bone pain.

On examination, there are no apparent skin lesions. However, cell phone photos show multiple, erythematous, slightly elevated papules or patches on her trunk (see Figure). Review of her previous labs shows a normal TSH and CBC in the last year. Her comprehensive metabolic profile shows slight elevation of her transaminases which is believed to be due to a fatty liver. Her BMI is 31 and her hemoglobin A1C is mildly elevated.