see also:

• dermatology
• localised rashes
• paediatric exanthems
• https://www.aafp.org/afp/2010/0315/p735.html

• hypersensitivity reactions
  • urticaria
  • erythema multiforme
  • drug eruption
    • morbilliform drug reaction
    • drug reactions with eosinophilia and systemic symptoms (drug reactions with eosinophilia and systemic symptoms (DRESS syndrome)):
      • aromatic anticonvulsants and other antiepileptics, sulphonamides, allopurinol, non-steroidal anti-inflammatory drugs (NSAIDs), and certain antibiotics
  • systemic lupus erythematosus (SLE) can be:
    • m/p rash similar to morbilliform drug reaction
    • photosensitivity rash
    • central face malar or “butterfly” violaceous erythema with a sharp cutoff at lateral margins
    • mucosal lesions
    • bullous rash like Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)
    • psoriasis-like rash
    • overlapping annular lesions
    • chronic form is discoid SLE - indurated hyperpigmented plaques mainly to head and neck
  • contact dermatitis
  • Grover disease - common, mainly truncal and upper arms, most often affects Caucasian men over 50 years of age with sundamaged skin
• viral exanthems
  • measles
  • EBV / glandular fever / infectious mononucleosis especially if amoxicillin has been taken
  • hand foot and mouth - often has buttock involvement in young children
  • Fifth disease (i.e., erythema infectiosum)
  • roseola (i.e., exanthem subitum, sixth disease)
  • rubella
  • rubeola
  • non-specific viral exanthems
• bacterial toxin related rashes:
  • scarlet fever
  • Kawasaki disease
  • meningococcaemia
  • toxic shock syndrome
• bacterial skin infections
  • folliculitis
• insects
  • multiple insect bites including bed bugs
  • scabies
  • rickettsial pox
  • lyme disease
  • Rocky Mountain spotted fever
• heat rash / miliaria rubra
• topical steroid withdrawal (TSW) rash
• subacute:
  • Pityriasis rosea
  • tinea corporis
• exacerbations of chronic conditions
  • psoriasis esp. guttate psoriasis
  • dermatitis herpetiformis

• hand foot and mouth (mucosal involvement mainly in young children)
• erythema multiforme major type
• mycoplasma (MIRM)
• systemic lupus erythematosus (SLE)
• Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) - early phase is non-blistering

• urticaria
• erythema multiforme
• drug eruption
• Kawasaki disease
• Toxic shock syndrome
• HIV seroconversion
• gonococcal
• secondary syphilis
• rubella
• scabies (in infants)
• Tinea corporis
• psoriasis

• urticaria
• meningococcal
• sepsis
• scabies

• measles (starts behind ears or on forehead at hairline)
• fifth disease (starts as slapped cheeks)
• rubella - facial rash usually clears as it spreads to other parts of the body
• scarlet fever - rash usually starts below the ears, neck, chest, armpits and groin before spreading to the rest of the body over 24 hours.

• morbilliform drug eruption
  • usually appears 1–2 weeks after starting the drug, but it may occur up to 1 week after stopping it
  • usually first appears on the trunk and then spreads to the limbs and neck
• Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) - these may be mac/pap in early stage
• many non-specific paediatric exanthems
• secondary syphilis - mainly trunk and extremities including palms and soles 4-10wks after primary infection

• EBV / glandular fever / infectious mononucleosis - usually faint and non-itchy, appearing first on the trunk and upper arms, extending to involve the face and forearms ¹⁾

• roseola - rarely spreads to involve the neck, face, arms and legs
• pityriasis rosea
  • herald patch on trunk usually; secondary plaques appear on trunk most often appearing from the top down, a few plaques may also appear on the thighs, upper arms, and neck, but are uncommon on the face, scalp, palms, or soles
• heat rash / miliaria rubra
  • mainly affects hot sweaty areas covered by clothing
• Grover disease (transient acantholytic dermatosis)
  • pruritic rash most often affects Caucasian men over 50 years of age with sundamaged skin and may involve upper arms

• hand foot and mouth - purplish vesicular lesions on fingers/toes then may get m/p rash on buttocks and mouth lesions
• erythema multiforme - these may be mac/pap in early stage
• mycoplasma - these may be mac/pap in early stage