Cold clue to a curious rash

Is immersion in icy water after a walk to blame for this active retiree’s pain and blotchy rash?

Jen, aged 67, enjoys an active retirement. A former health professional, she focuses on improving her health as she ages, and is physically active — hiking, gardening and swimming. Jen has a background of Graves’ disease, in remission for 10 years.

She is a lifelong non-smoker who takes no medications. She consumes a wholefood low carbohydrate diet.