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Rash is a topic covered in the 5-Minute Emergency Consult.

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  • Morphology, distribution, associated systemic symptoms, and the evolution of a rash are important clinical considerations in identifying a dermatologic emergency
  • Presentations of erythroderma, blistering/desquamation, purpura, and skin pain with systemic symptoms are warning signs of a potential emergency
  • Abnormal skin lesions due to an inflammatory reaction that can be classified into patterns with distinctive clinical features
  • Vesiculobullous lesions:
    • Fluid-filled swelling of the skin or sloughing due to disruption of epidermal/dermal integrity
  • Purpura and petechiae:
    • Failure of normal vascular integrity/hemostatic mechanisms
    • Do not blanch on palpation
  • Erythema:
    • Erythroderma when covering ≥90% of the skin surface
    • Vascular dilatation of the superficial vessels leading to red macular lesions
    • Blanches on palpation
    • Figurate erythema:
      • Erythema classified by its particular annular or arcuate shape
  • Papulosquamous:
    • Papules and scaly desquamation of the skin
    • Lesions may also be red and macular
    • Classified into psoriasiform, pityriasiform, lichenoid, annular, and eczematous
  • Nodules:
    • Secondary to prolonged inflammatory response, cyst, or infiltrative process
    • Granulomatous lesions:
      • “Apple jelly” appearance when pressed with glass slide


Etiology/Differential Diagnoses
  • Vesiculobullous lesions:
    • Toxic epidermal necrolysis (mucosal and >30% body surface area involvement)
    • Stevens–Johnson syndrome (mucosal and ≤10% body surface area involvement)
    • Pemphigus vulgaris
    • Bullous pemphigoid
    • Disseminated herpes simplex
    • Herpes zoster
    • Varicella
    • Smallpox
    • Vaccinia
    • Allergic contact dermatitis
  • Purpura and petechiae:
    • Meningococcemia
    • Gonococcemia
    • Purpura fulminans/disseminated intravascular coagulopathy (DIC)
    • Rocky Mountain spotted fever (RMSF):
      • Pronounced prodrome of fever, headache, myalgia, rash, peripheral moves to palms/soles
    • Ecthyma gangrenosum:
      • Pseudomonas infections in critically ill and immunocompromised patients
    • Babesiosis: Similar to RMSF, rash less often, frequent coinfection with Lyme
    • Vasculitis
    • Multiple systemic illnesses (see chapter on Purpura)
  • Erythroderma:
    • Toxic shock syndrome
    • Drug-induced
    • Psoriasis
    • Seborrheic dermatitis
    • Mycosis fungoides
    • Lymphoma of the skin
  • Erythematous rashes:
    • Localized:
      • Cellulitis
      • Early necrotizing fasciitis with concomitant skin pain
    • Diffuse:
      • Staphylococcal scalded skin syndrome
      • Toxic shock syndrome
      • Drug-induced, including drug reaction with eosinophilia and systemic symptoms (DRESS)
      • Viral exanthema
  • Figurate erythema:
    • Erythema chronicum migrans (large red ring that arises around a tick bite):
      • Lyme disease
    • Erythema multiforme:
      • Mycoplasma pneumoniae
      • Herpes simplex
      • Drug reaction leading to Steven–Johnson syndrome
    • Urticaria:
      • Allergic reaction from drugs, food, infection, pressure, heat, or cold
  • Papulosquamous:
    • Psoriasiform:
      • Psoriasis
      • Seborrheic dermatitis
      • Drug-induced
    • Pityriasiform:
      • Pityriasis rosea
      • Secondary syphilis
      • Tinea versicolor
    • Lichenoid:
      • Lichen planus
      • Drug-induced
    • Annular:
      • Tinea
      • Figurate erythema (see below)
    • Eczematous:
      • Atopic dermatitis
      • Allergic contact dermatitis
      • Irritant dermatitis
  • Nodules:
    • Granulomatous disease:
      • Sarcoid
      • Granuloma annulare
      • Infectious: Leprosy, tuberculosis, deep fungal infection
    • Panniculitis:
      • Erythema nodosum
    • Lymphoma of the skin
    • Cysts
    • Tumors and metastatic disease

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Rosen, Peter, et al., editors. "Rash." 5-Minute Emergency Consult, 5th ed., Lippincott Williams & Wilkins, 2016. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307138/all/Rash.
Rash. In: Rosen P, Shayne P, Barkin AZ, et al, eds. 5-Minute Emergency Consult. 5th ed. Lippincott Williams & Wilkins; 2016. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307138/all/Rash. Accessed April 24, 2019.
Rash. (2016). In Rosen, P., Shayne, P., Barkin, A. Z., Wolfe, R. E., Hayden, S. R., Barkin, R. M., & Schaider, J. J. (Eds.), 5-Minute Emergency Consult. Available from https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307138/all/Rash
Rash [Internet]. In: Rosen P, Shayne P, Barkin AZ, Wolfe RE, Hayden SR, Barkin RM, Schaider JJ, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2016. [cited 2019 April 24]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307138/all/Rash.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Rash ID - 307138 ED - Rosen,Peter, ED - Shayne,Philip, ED - Barkin,Adam Z, ED - Wolfe,Richard E, ED - Hayden,Stephen R, ED - Barkin,Roger M, ED - Schaider,Jeffrey J, BT - 5-Minute Emergency Consult UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307138/all/Rash PB - Lippincott Williams & Wilkins ET - 5 DB - Emergency Central DP - Unbound Medicine ER -