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151 Childhood Viral Rashes Made Simple – Exanthems, HFMD, Chickenpox & the Patterns That Show Up on PANCE

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Viral Skin Conditions: Exam Organization

Viral dermatologic conditions are best approached by age, distribution, and systemic involvement rather than by memorizing individual viruses. Confusion on exams often occurs when pediatric viral exanthems are tested against one another.

Categories for exam organization:
• Pediatric systemic viral patterns (viral exanthems, hand-foot-and-mouth disease, varicella)
• Localized viral lesions (HSV, molluscum contagiosum, verrucae)
• Sexually transmitted viral dermatoses (condyloma acuminatum)

Childhood Exanthems

• Exanthem refers to a widespread rash associated with a systemic illness
• Traditionally described using numbered childhood diseases
• Most are viral; scarlet fever is bacterial
• On exams, these are differentiated by fever timing, rash distribution, and associated findings
• Do not worry about memorizing historical numbering

Measles (Rubeola)

First Disease

Clinical Presentation

• High fever
• Cough, coryza, conjunctivitis
• Diffuse maculopapular rash spreading head to toe
• Koplik spots on buccal mucosa prior to rash

Scarlet Fever

Second Disease (bacterial, not viral)

Clinical Presentation

• Fever and sore throat
• Diffuse erythematous sandpaper rash
• Strawberry tongue
• Caused by Group A Streptococcus

Rubella

Third Disease

Clinical Presentation

• Mild systemic symptoms
• Diffuse maculopapular rash
• Posterior auricular and occipital lymphadenopathy
• Often milder than measles

Erythema Infectiosum (Parvovirus B19)

Fifth Disease

Clinical Presentation

• Slapped cheek facial rash
• Followed by lacy, reticular rash on trunk and extremities
• Child often otherwise well

Roseola Infantum (Human Herpesvirus 6)

Sixth Disease

Clinical Presentation

• High fever for several days
• Rash appears after the fever resolves
• Common in infants and young children

Treatment for Exanthems

• Supportive care for viral exanthems
• Antibiotics for scarlet fever

Exam Keys

• Slapped cheek: Parvovirus B19 (fifth disease)
• Rash after fever resolves: Roseola (sixth disease)
• Sandpaper rash with sore throat: Scarlet fever (not viral)
• Cough, coryza, conjunctivitis: Measles
• Numbering is historical; focus on clinical patterns

Hand-Foot-and-Mouth Disease

• Common viral illness most often caused by Coxsackievirus A
• Primarily affects infants and young children

Clinical Presentation

Rash / Skin Findings:
• Vesicular lesions on palms and soles
• May involve buttocks and extremities
• Lesions are small and painful

Oral Findings:
• Painful oral ulcers or vesicles
• Involve tongue, buccal mucosa, and soft palate
• May decrease oral intake

Systemic Features:
• Low-grade fever
• Malaise
• Sore throat

Exam Clue:
• Young child with fever, painful oral sores, and vesicular rash on hands and feet

Treatment

• Supportive care
• Hydration and pain control
• No antiviral therapy

Exam Keys

• Vesicles on palms and soles
• Oral ulcers distinguish HFMD from most other exanthems
• Common in daycare-aged children
• Self-limited illness

Varicella (Chickenpox)

• Primary infection with varicella-zoster virus
• Most common in unvaccinated children

Clinical Presentation

Rash / Skin Findings:
• Vesicular rash in multiple stages (papules, vesicles, crusts)
• Lesions appear in crops
• Begins on trunk and spreads to face and extremities
• Pruritic lesions

Systemic Features:
• Fever and malaise
• Symptoms often precede rash by 1 to 2 days

Exam Clue:
• Child with fever and itchy vesicular rash in multiple stages beginning on the trunk

Treatment

• Supportive care in healthy children
• Acyclovir for adolescents, adults, immunocompromised patients, or severe disease

Exam Keys

• Multiple lesion stages at once
• Trunk predominance helps distinguish from HFMD
• Vesicular lesions rather than maculopapular

Herpes Simplex Virus (HSV)

• Localized viral infection caused by HSV-1 or HSV-2
• Characterized by recurrent outbreaks

Clinical Presentation

Rash / Skin Findings:
• Grouped vesicles on an erythematous base
• Vesicles rupture into painful ulcers
• Typical locations:
• HSV-1 oral/labial
• HSV-2 genital or perianal

Associated Symptoms:
• Pain, burning, or tingling preceding lesions
• Local lymphadenopathy may occur

Exam Clue:
• Painful, grouped vesicles with history of recurrence

Treatment

• Acyclovir, valacyclovir, or famciclovir
• Episodic or suppressive therapy

Exam Keys

• Grouped vesicles indicate HSV
• Painful lesions distinguish HSV from molluscum
• Recurrent outbreaks are classic
• Tingling or burning prodrome

Molluscum Contagiosum

• Benign viral infection caused by a poxvirus
• Common in children, sexually active adults, and immunocompromised patients

Clinical Presentation

Rash / Skin Findings:
• Small, firm, dome-shaped papules
• Central umbilication is characteristic
• Flesh-colored or pearly
• Common on trunk, extremities, and face in children
• Usually painless and nonpruritic

Associated Features:
• Spread by skin contact or autoinoculation
• Lesions may become inflamed as they resolve

Exam Clue:
• Child with multiple painless umbilicated papules on trunk or extremities

Treatment

• Observation (self-limited)
• Curettage or cryotherapy if persistent or bothersome

Exam Keys

• Umbilicated papules
• Painless lesions distinguish from HSV
• Common in children
• Often resolves spontaneously

Verrucae (Warts)

• Benign epithelial proliferations caused by HPV
• Spread by direct contact or autoinoculation

Clinical Presentation

Rash / Skin Findings:
• Hyperkeratotic papules or plaques
• Rough, irregular surface
• May have black punctate dots (thrombosed capillaries)

Common Types:
• Verruca vulgaris: hands and fingers
• Plantar warts: soles, painful with pressure
• Flat warts: face or extremities

Associated Features:
• Usually painless except plantar lesions
• Slow growing
• May persist for months to years

Exam Clue:
• Rough, hyperkeratotic lesion with black dots on hands or soles

Treatment

• Observation (often self-limited)
• Salicylic acid or cryotherapy if treatment desired

Exam Keys

• Black punctate dots (thrombosed capillaries)
• Rough hyperkeratotic surface
• HPV related but not sexually transmitted (except condyloma)
• Plantar warts may be painful with walking

Condyloma Acuminatum (Genital Warts)

• Sexually transmitted infection caused by HPV, most commonly types 6 and 11
• Usually benign but requires STI context

Clinical Presentation

Rash / Skin Findings:
• Soft, flesh-colored or gray papules
• Cauliflower-like or verrucous surface
• Single or multiple lesions
• Involves external genitalia, perianal region, or cervix

Associated Features:
• Usually painless
• May itch, bleed, or irritate
• Often persistent without treatment

Treatment

• Topical agents (imiquimod, podophyllotoxin)
• Cryotherapy or excision for extensive or refractory disease
• Recurrence is common

Exam Keys

• Cauliflower-like genital lesions
• Low-risk HPV types 6 and 11
• Distinct from verrucae on hands and feet
• Does not imply malignancy but warrants STI counseling