Rashes (kids)

LESION	DESCRIPTION	PATHOGENS ORINFECTION
a)Maculopapular rash	macules – red/pink discrete flat areas, blanch on pressure papules – solid,raised hemispherical lesions, tiny, blanch on pressure	VRS – Measles, rubella, roseola, erythema infectiosum, EBV, echovirus, HBV, HIV BACT – Erythema marginatum, scarlet fever, erysipelas, 2° syphilis, leptospirosis, Lyme dzs,  RICK – Rocky Mountain Spotted fever, Typhus OTH – RA, Kawasaki dis, drug rxn
b) Diffuse erythroderma	– thickened, scaly skin on palms and soles	BACT – Scarlet fever, Toxic Shock Syndrome, Staph SSS FUNGI – Candida albicans OTH – Kawasaki syndrome
c) Urticarial rash	swelling of the lesions appear n resolve rapidly	VRS – EBV, Hep B, HIV BACT – M.pneumonia,Grp A strep . OTH – Drug rxn
d) vesicular, pustular, bullous	-Vesicular – raised hemispherical lesions,< 0.5cm, contain clear fluid-Pustular, bullous – raised hemispherical lesion, >0.5cm, contain clear/purulent fluid	VRS – HSV, VZV,Coxsackievirus BACT – Staph.SSS,Staph. Bullous impetigo, Strep. crusted impetigo OTH – Toxic epidermal necrolysis, Steven- Johnson Syndrome. RICK – Rickettsial pox
e) Petechial – purpuric	non-blanching red/purple spots	VRS – Atypical measles, congenital rubella, CMV, enterovirus, HIV, HF viruses BACT – Sepsis (meningococcal, gonococcal, pneumococcal, Hib), IE RICK – Rocky mountain spotted fvr FUNGI – Aspergillus, mucor OTH – Vasculitis, thrombocytopenia, Henoch-Schönlein purpura, malaria
	Erythema Nodosum- tender red nodules, due to exudation of blood and serum	VRS – EBV, HBV BACT – Group A Streptococcus, TB, yersinia, Cat- Scratch Dzs FUNGI –Coccidiomycosis, histoplasmosis OTH – Sarcoidosis, Inf. Bowel dzs, OCP, SLE, Behçet dzs

Petachial Rash

non-blanching erythematous (reddish) skin lesions resulting from the extravasation of blood due to intradermal capillary leakage

• Petechiae: are lesions the size of a pin-head (different sources say less than 2 mm or 3 mm, others up to 5 mm)
• Purpura: are lesions that are larger than this (and may or may not be palpable).

• Infection
  • serious bacterial illnesses
    • classically meningococcemia, but also others infections such as streptococcus, H. influenzae and infective endocarditis
  • viral infections (e.g. influenza, measles, enteroviruses and parvovirus)
  • rickettsiae 
  • Rocky Mountain Spotted Fever in North America
  • Epidemic typhus
  • Queensland tick typhus
• Mechanical
  • coughing or vomiting (limited to the head and neck regions)
  • local pressure or tourniquet application (e.g. petechiae distal to the tourniquet)
  • strangulation
• Hematological
  • thrombocytopenia (platelets <100 x 10E9/L)
    • ITP (immune thrombocytopenic purpura)
    • Leukemia
    • Hypersplenism.
  • platelet dysfunction — e.g. congenital, drugs and renal failure.
• Vascular
  • Vasculitis
    • Henoch-Schonlein purpura
  • Scurvy (classically perifollicular pupura on the lower limbs)
  • drugs e.g. steroids
  • Cushing’s syndrome
  • fat embolism
  • dysproteinemia