Chilblains are painful patches on the skin caused by inflammation of small blood vessels in the skin in response to cold or damp, but not freezing, temperatures. Chilblains most commonly form on the fingers or toes. The patches are red or bluish-colored and may be painful, tender, or itchy. Females and people with lower body mass index (BMI) are more likely to get chilblains. It is also known as pernio or perniosis.
Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.