Primary Lesions

Secondary Lesions

Exanthema Diseases (Eruptive Fever / Rash Diseases)

The Classic "Numbered" Exanthems

Detailed Disease Profiles

1st Disease - Measles (Rubeola)

• Cause: Measles virus
• Prodrome: 3 C's - Cough, Coryza (runny nose), Conjunctivitis + high fever
• Pathognomonic sign: Koplik spots - red/white-blue macules on buccal mucosa (appear before rash)
• Rash: Maculopapular (morbilliform), starts on face/hairline, spreads downward to trunk and extremities; coalescent
• Duration: 3-5 days
• Complications: Pneumonia, encephalitis, subacute sclerosing panencephalitis (SSPE)
• Prevention: MMR vaccine (notifiable disease)

2nd Disease - Scarlet Fever (Scarlatina)

• Cause: Streptococcus pyogenes producing pyrogenic (erythrogenic) exotoxin
• Signs: Pharyngitis + characteristic rash
• Rash: Diffuse red "sandpaper texture," starts on neck/upper chest, spares face; circumoral pallor
• Enanthem: Strawberry tongue (white at first, then red strawberry tongue)
• Other features: Pastia's lines (linear petechiae in skin folds, e.g., antecubital fossa)
• Resolution: Desquamation beginning at palms and soles (6-9 days)
• Treatment: Penicillin (to prevent rheumatic fever)
• Notifiable disease

3rd Disease - Rubella (German Measles / 3-Day Measles)

• Cause: Rubella virus (Togavirus)
• Rash: Fine, pink maculopapular; spreads from hairline/face downward; clears from original sites as it spreads (unlike measles)
• Enanthem: Forchheimer spots - petechiae on soft palate
• Key feature: Postauricular & suboccipital lymphadenopathy
• Most dangerous: Congenital Rubella Syndrome - if acquired in 1st trimester: cataracts, cardiac defects (PDA), deafness, microcephaly
• Prevention: MMR vaccine (notifiable disease)

4th Disease - Filatov-Dukes Disease

• Cause: Disputed - possibly Staphylococcus aureus exfoliative toxin
• Note: Some authorities consider this entity does not exist as a separate disease; now thought to overlap with Staphylococcal Scalded Skin Syndrome (SSSS)
• Rash: Desquamating skin, similar to mild scalded skin syndrome

5th Disease - Erythema Infectiosum (Slapped Cheek Disease)

• Cause: Parvovirus B19
• Incubation: 10-20 days
• Rash - 3 stages:
  1. Stage 1: Intense red "slapped cheek" appearance on face (fiery red cheeks)
  2. Stage 2: Lacy/reticular maculopapular rash on trunk and extremities
  3. Stage 3: Rash fades but recurs with heat, exercise, sun (weeks-months)
• Key danger: In pregnancy - hydrops fetalis (fetal anemia from viral tropism for erythroid progenitor cells)
• In sickle cell/hemolytic anemia patients: Aplastic crisis
• Season: Primarily spring; school-age children (5-15 yrs)

6th Disease - Roseola Infantum (Exanthem Subitum)

• Cause: HHV-6B (Human Herpesvirus 6B; rarely HHV-7)
• Age: 6 months to 2 years (peak); up to 80% of children infected by age 2
• Classic presentation:
  1. High fever (38-40°C) for 3-5 days - child appears relatively well
  2. Fever abruptly breaks - then rash appears (the "sudden rash" = subitum)
• Rash: Rose-pink macules/papules on trunk, spreading to neck and extremities; blanching; lasts 1-3 days
• Complication: Febrile seizures (most common cause of first febrile seizure in infants)
• Transmission: Saliva; incubation 5-15 days
• Immunocompromised risk: Reactivation can cause encephalitis, pneumonitis
• - Fitzpatrick's Dermatology, Tintinalli's Emergency Medicine, Family Medicine Textbook

Other Important Exanthems

Quick Memory: Rash Timing in Fever

Sources: Fitzpatrick's Dermatology, Tintinalli's Emergency Medicine, Harrison's Principles of Internal Medicine, Sherris & Ryan's Medical Microbiology, Textbook of Family Medicine