Prolonged exposure to coldtemperatures can have a profoundeffect on the skin.When tissues are exposed toabove-freezing temperatures,localized vasoconstriction and increasedblood viscosity reduce bloodflow and decrease the amount ofoxygen available to tissues. Whentissues are exposed to freezing temperatures,water within those tissueschanges into ice crystals; this resultsin either intracellular or extracellulardamage and tissue necrosis.
Prolonged exposure to coldtemperatures can have a profoundeffect on the skin.When tissues are exposed toabove-freezing temperatures,localized vasoconstriction and increasedblood viscosity reduce bloodflow and decrease the amount ofoxygen available to tissues. Whentissues are exposed to freezing temperatures,water within those tissueschanges into ice crystals; this resultsin either intracellular or extracellulardamage and tissue necrosis.Here, I discuss such cold-relatedskin disorders as chilblains, cold ur-ticaria, panniculitis, frostbite, Raynaud'sphenomenon, cutis marmorata,and asteatotic eczema. I offer cluesto their diagnosis and suggest appropriatetherapies.CHILBLAINS
Also called perniosis, chilblainsdevelops when the skin is exposed toabove-freezing temperatures in a dampenvironment. Initially, vasoconstrictionoccurs; vasodilation-as part of rewarming-follows. Clinically, chilblainsappears as erythema and swelling with"doughy" nodules and plaques. Pain,burning, or pruritus may be present.Frequently affected areas include tipof the nose, pinnas, fingers, and toes;the skin that overlies fatty areas, suchas on the thighs and abdomen (Figure1), also can be involved.Histopathologic features includemarked edema in the papillary dermisand edema within the blood vesselwalls. A mononuclear cell perivasculardermal infiltrate is also found.Chilblains can be avoided bywearing warm clothing and by stayingin dry, heated buildings duringthe winter. If chilblains does occur,the acute lesions can be treated byrest and by immersion in warmwater. The lesions usually resolvewithin a few weeks. Calcium channelblockers, such as nifedipine, havebeen shown to prevent recurrencesin persons with chronic chilblains.COLD URTICARIA
A type of physical urticaria, coldurticaria may be either familial or idiopathic.The idiopathic form canoccur in susceptible persons from exposureto cold temperatures. Such exposuresas eating cold foods or swimmingin cold water can precipitate"hive-like," erythematous, edematousplaques. Urticarial lesions that arisefrom ingestion of cold foods may belocalized to the mouth; broader exposurecan result in more widespreadlesions (Figure 2). Pruritus and systemicsymptoms, such as hypotension,may be associated with urticaria.To confirm the diagnosis ofcold urticaria, place an ice cube onthe patient's forearm. If a whealdevelops at the site of contact, thetest is positive.The histopathologic features ofacute urticaria include interstitial dermaledema and dilated vessels withendothelial swelling.A very rare familial form of coldurticaria is inherited as an autosomaldominant trait. It usually presents initiallyat an early age when affectedpersons are exposed to a cold environment.Patients develop urticarialplaques that can be associated withfever and joint pain. The condition isa response to generalized coolingrather than to the local application ofa cold substance. Thus, affected personsexhibit no response to the diagnosticice cube test.Avoidance of exposure to coldis the best prevention. However, ifcold urticaria develops, oral antihistamines,such as hydroxyzine hydrochlorideand doxepin, may be helpful.Caution patients who have had a positiveice cube test to avoid swimmingin cold water.COLDPANNICULITIS
Because of its clinical presentationin children, cold panniculitis hasbeen called "Popsicle panniculitis."Erythematous nodules or plaques,which are sometimes associated withpain or pruritus, may develop severaldays after exposure on the face ofchildren who eat iced food, such as aPopsicle. This condition is uncommonin adults.Initially, histopathologic examinationshows perivascular infiltrate oflymphocytes and macrophages at thejunction of the dermis and subcutaneousfat. Rupture of fat cells surroundedby an inflammatory infiltrateusually occurs after a few days.The application of ice for about10 minutes causes edematousplaques to form at the site within aday. The lesions of cold panniculitisusually resolve spontaneously withina few weeks. The best treatment is toavoid prolonged contact with icedproducts.FROSTBITE
Exposure to temperatures thatare below 0oC (32oF) causes tissuesresponse varies with the degree ofcold exposure and with the susceptibilityof the individual. Previous trauma,older age, smoking, and peripheralvascular disease are predisposingfactors. The most commonly affectedsites are ears, nose, fingers, and toes.Initially, the skin becomes whiteand the area may have decreasedsensation, but deeper tissues are notaffected. In more severe frostbite,deeper tissues are involved, whichcauses the skin to become firm; completeanesthesia may occur. Bullaecan develop (Figure 3) within severaldays and tissue necrosis (Figure 4)may result, necessitating amputationof the affected area.A skin biopsy may show bullae,necrotic changes, and/or an overlyingeschar.Before treating frostbite, makesure the patient is stabilized and therisk of further cold exposure is unlikely.Rapidly rewarm the affected area ina warm bath or with warm compress- es at temperatures between 37oC and43oC (100oF and 110oF).Continue rewarminguntil the area becomes redand flushed.RAYNAUD'SPHENOMENON
Vasospasm induced by cold exposurecauses Raynaud's phenomenon,which may occur as an isolatedentity or as part of a connective tissuedisorder, such as lupus erythematosusor scleroderma. The idiopathicform of the condition is referred to asRaynaud's disease.A sequence of skin colorchanges defines the disorder's progression.First, vasoconstrictioncauses the affected digits to turnwhite (Figure 5). Next, with theonset of the cyanotic phase, thefingers and/or toes become blue.Lastly, reactive hyperemia causesthe digits to turn red (Figure 6).This can be associated with significantpain.Evaluate patients who presentwith Raynaud's phenomenon for associatedsystemic diseases, includingrheumatologic or vascular diseasesand hematologic abnormalities,which may require treatment.In addition to advising patients toavoid exposure to the cold, considerprescribing a vasodilator, such as acalcium channel blocker, which maybe helpful in treating the peripheralvasoconstriction.CUTISMARMORATA
A physiologic mottling of theskin, or cutis marmorata, is causedby cold-induced vasoconstrictionand hypoxia followed by vasodilation.A red-blue blotchy reticulated,or net-like, pattern is characteristic.The bluish pigmentation is thoughtto reflect venous blood; whereas thereddish component may result fromincomplete oxygen dissociation.Cutis marmorata is common ininfants (Figure 7) and young children.It tends to become less apparentwith age; however, the disordercan occur as a benign condition inadults as well (Figure 8).The reticulated mottling of theskin usually is transient and fadeswith warming.ASTEATOTICECZEMA
One of the most common winterdermatoses is dryness of the skin, orasteatotic eczema. This condition isoften very pruritic. Cold temperaturesand low humidity in winter cause fissuresin the stratum corneum that resultin scaly, dry, and cracked skin(Figures 9 and 10). Asteatotic eczemais also called eczema craquel.Medium- to high-potency topicalcorticosteroids may relievethe cutaneous symptoms. Counselyour patients to prevent recurrencesby bathing less often, using coolerbath water and an emollient-basedsoap, and generously applyingmoisturizers.