This article explores the location and function of extensor surfaces and which skin conditions often affect these areas.
Those on extensor surfaces are more prone to injury andinflammationdue to the action of bending a joint.
Why these specific surfaces are affected remain somewhat of a mystery.
Illustration by Brianna Gilmartin, Verywell
Over time, this causes the skin to thicken, a condition known asepidermal hyperplasia.
Not surprisingly, skin trauma and localized inflammation are two of the key triggers of psoriasis.
The termatopicis used to describe diseases due to an inappropriate immune system reaction, such asasthmaandhay fever.
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This is unlike an autoimmune disorder in which cells are directly attacked.
This photo contains content that some people may find graphic or disturbing.
As with psoriasis, nummular eczema is not well understood by scientists.
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Common drug triggers include barbiturates, penicillin, phenytoin, and sulfonamide.
Viral and bacterial infections likeherpes simplex virusandMycoplasma pneumoniaecan also incite a reaction.
Dermatitis Herpetiformis
Dermatitis herpetiformisis a chronic skin disorder closely linked toceliac diseaseandgluten sensitivity.
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Dermatitis herpetiform is due to the accumulation ofimmunoglobulin A (IgA)in the epidermis.
This includes the preponderance of lesions on extensor surfaces, including the knees and elbows.
Summary
Extensor surfaces are the skin surfaces outside a joint.
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Psoriasis can occur anywhere.
Plaque psoriasis, which is the most common bang out, typically occurs on extensor surfaces.
A rare key in called inverse psoriasis occurs on flexor surfaces.
Dermatitis herpetiformis looks like a cluster of bumps that can appear similar to mild acne or eczema.
It is usually itchy.
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2014;4(8):a015354.
Trayes KP, Love G, Studdiford JS.Erythema multiforme: recognition and management.Am Fam Physician.
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National Institute of Diabetes and Digestive and Kidney Diseases.Dermatitis herpetiformis.
