title: Rash Decisions: An Approach to Dangerous Rashes Based on Morphology.
abstract: BACKGROUND
  Rash is a common complaint in the emergency department. Many causes of rash are benign; however, some patients may have a life-threatening diagnosis.
  
  
  OBJECTIVE
  This review will present an algorithmic approach to rashes, focusing on life-threatening causes of rash in each category.
  
  
  CONCLUSIONS
  Rash is common, with a wide range of etiologies. The differential is broad, consisting of many conditions that are self-resolving. However, several conditions associated with rash are life threatening. Several keys can be utilized to rapidly diagnose and manage these deadly rashes. Thorough history and physical examination, followed by consideration of red flags, are essential. This review focuses on four broad categories based on visual and tactile characteristic patterns of rashes: petechial/purpuric, erythematous, maculopapular, and vesiculobullous. Rashes in each morphologic group will be further categorized based on clinical features such as the presence or absence of fever and distribution of skin lesions.
  
  
  CONCLUSIONS
  Rashes can be divided into petechial/purpuric, erythematous, maculopapular, and vesiculobullous. After this differentiation, the presence of fever and systemic signs of illness should be assessed. Through the breakdown of rashes into these classes, emergency providers can ensure deadly conditions are considered.
authors.affiliation: BerbeeWalsh Department of Emergency Medicine, University of Wisconsin School of Public Health, Madison, Wisconsin.
authors.forename: Jamie
authors.initials: J
authors.lastname: Santistevan
authors.affiliation: Department of Emergency Medicine, San Antonio Military Medical Center, Fort Sam Houston, Texas.
authors.forename: Brit
authors.initials: B
authors.lastname: Long
authors.affiliation: Department of Emergency Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas.
authors.forename: Alex
authors.initials: A
authors.lastname: Koyfman
mesh_terms: D003937:Diagnosis, Differential; D004890:Erythema / Q000175:diagnosis / Q000209:etiology; D005076:Exanthema / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology*; D005334:Fever / Q000209:etiology; D006801:Humans; D011693:Purpura / Q000175:diagnosis / Q000209:etiology; D012871:Skin Diseases / Q000175:diagnosis*; D012872:Skin Diseases, Vesiculobullous / Q000175:diagnosis / Q000209:etiology
keywords: erythema; maculopapular; petechiae; purpura; rash; vesiculobullous