The correct answer is:

frostnip

Educational Objective:

Explain the terminology associated with cold-induced injuries.

Key Points:

Frostnip refers to a cold-induced, localized area accompanied by both pain and paresthesia. Frostnip is rapidly reversible with rewarming and does not result in tissue damage.

Explanation:

This patient has frostnip, which is associated with significant vasoconstriction and is accompanied by discomfort in the involved parts (see Figure 1). If it is left unattended, frostnip can eventually progress to frostbite.

Figure 1 - Frostnip

Pernio, also referred to as chilblain, is characterized by localized inflammatory lesions from acute or repetitive exposure to damp cold temperatures above freezing.

Chilblains are thought to be due to cold-damaged microvessels that leak and cause inflammation, leading to small, red swellings that are usually painful, itchy, and tender to touch. In severe cases, the surface of the skin may break and sores or blisters can develop. The inflammation characteristic of chilblain is similar (albeit much less severe) to that found when frostbitten extremities are thawed (see Figure 2).

Figure 2 - Local inflammation due to chilblain.

Frostbite is a localized, cold-induced ischemic injury that results in temporary or permanent tissue damage (depending on the depth of frostbite). In contrast to frostnip and chilblain, frostbitten tissues become pain free, which makes a person lose awareness and, therefore, protective behavioral reflexes.

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