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rash_linear

the linear skin lesion or rash

see also:

introduction

  • the finding of linear skin lesions can often assist in the diagnosis of skin rashes as the list of differentials tends to be more limited.

DDx

striae

  • striae distensia

dermographism

  • skin becomes raised and inflamed with a localised wheal reaction when stroked, scratched, rubbed, and sometimes even slapped
  • 4-5% of population have this familial skin disorder (also called dermatographism)
  • see also urticaria

burrowing lesions

  • scabies particularly in digital web spaces has short linear lesions

Koebner phenomenon

  • skin lesions occuring in lines of trauma
  • linear external contact:
    • toxicodendron dermatitis (eg. poison ivy)
    • other contact dermatitis (eg. wrist bands, watches, rings, etc)
  • direct inoculation of viral particles:
    • warts
    • molluscum contagiosum
  • other conditions with linear lesions resulting from scratching
    • pityriasis rubra pilaris
    • lichen planus:
      • a chronic mucocutaneous disease that affects the skin, tongue, and oral mucosa.
      • the “5 Ps”: well-defined pruritic, planar, purple, polygonal papules
      • commonly affected sites are near the wrist and the ankle
      • tends to heal with prominent blue-black or brownish discoloration that persists for a long time
    • lichen nitidus
      • chronic rash characterized by 1-2 mm, discrete and uniform, shiny, flat-topped, pale flesh-colored or reddish-brown papules
      • usually affects children and young adults
      • linear pattern is common, especially on the forearms
    • vitiligo
      • depigmentation
    • lichen sclerosus
      • white patches on the skin, which may cause scarring
      • women 10x more affected than males. Mainly arises at menopause, and usually in the genital region
    • elastosis perforans serpiginosa
      • rare condition with serpiginous lesions
    • keratosis follicularis (Darier disease)
      • Darier's is a rare autosomal dominant condition characterized by dark crusty patches on the skin, sometimes containing pus
    • erythema elevatum diutinum
      • rare vasculitic condition thought to be paraneoplastic
  • pathergy:
    • skin lesions following minor trauma
    • pyoderma gangrenosum
    • Behçet's disease

linear skin fold lesions

  • capillary vasculitis processes
    • scarlet fever - Pastia's lines

dermatomal distribution

  • herpes zoster

conditions distributed along Blaschko's lines

  • embryonal skin lines not usually visible but which may become evident in certain conditions forming V shape on the back, S swirls on anterior trunk and wavy lines on the scalp
  • pigmentory disorders
  • acquired skin rashes:
  • genetic disorders

lacy reticular rashes

  • livido reticularis
    • common in those with pronounced reaction to cool weather
    • is much less commonly is caused by underlying conditions such as cryoglobulinemia
  • erythema ab igne
    • localized areas of reticulated erythema and hyperpigmentation due to chronic and repeated exposure to infrared radiation eg. laptops on bare thighs, heat packs, sitting near an open fire
  • lichen planus in oral mucosa
  • fifth disease (slapped check) usually develop lacy rash on inner aspect of upper arms

serpiginous cutaneous lesions

  • creeping cutaneous larva migrans
  • elastosis perforans serpiginosa
    • rare condition with serpiginous lesions

circular lesions

  • tinea (ringworm)
  • erythema multiforme - target lesions
rash_linear.txt · Last modified: 2011/10/18 05:45 by gary