ABD Pediatric Dermatology 3 — Questions and Answers
Question 1: A 5-year-old presents with honey-colored crusted erosions around the nose and mouth. What is the most common causative organism?
- Streptococcus pneumoniae
- Staphylococcus aureus (Correct answer)
- Pseudomonas aeruginosa
- Haemophilus influenzae
Correct answer: Staphylococcus aureus
Non-bullous impetigo is most commonly caused by Staphylococcus aureus.
Question 2: An infant develops widespread flaccid bullae and superficial desquamation with a positive Nikolsky sign but spares mucous membranes. What is the diagnosis?
- Toxic epidermal necrolysis
- Staphylococcal scalded skin syndrome (Correct answer)
- Bullous pemphigoid
- Stevens-Johnson syndrome
Correct answer: Staphylococcal scalded skin syndrome
SSSS is caused by staphylococcal exfoliative toxins, cleaves the granular layer, and characteristically spares mucosa.
Question 3: A child has multiple dome-shaped umbilicated papules on the trunk. What is the causative agent?
- Human papillomavirus
- Poxvirus (Correct answer)
- Herpes simplex virus
- Coxsackievirus
Correct answer: Poxvirus
Molluscum contagiosum is caused by a poxvirus and produces umbilicated papules.
Question 4: A 4-year-old presents with fever, a 'slapped cheek' facial erythema, followed by a lacy reticular rash on the extremities. What is the etiology?
- Measles virus
- Parvovirus B19 (Correct answer)
- Human herpesvirus 6
- Rubella virus
Correct answer: Parvovirus B19
Erythema infectiosum (fifth disease) is caused by parvovirus B19 with the classic slapped-cheek appearance.
Question 5: A child with tuberous sclerosis is examined for cutaneous findings. Which lesion is a well-recognized diagnostic criterion?
- Café-au-lait macules
- Ash-leaf macules (Correct answer)
- Port-wine stain
- Aplasia cutis
Correct answer: Ash-leaf macules
Hypopigmented ash-leaf macules are an early cutaneous marker of tuberous sclerosis.
Question 6: A neonate has a hairless, yellow-orange plaque on the scalp present at birth that thickens and becomes verrucous at puberty. What is the diagnosis?
- Nevus sebaceus of Jadassohn (Correct answer)
- Aplasia cutis congenita
- Congenital melanocytic nevus
- Epidermal nevus
Correct answer: Nevus sebaceus of Jadassohn
Nevus sebaceus presents as a hairless yellow-orange scalp plaque that becomes verrucous with hormonal stimulation.
Question 7: A febrile 1-year-old develops high fever for 3 days that abruptly resolves, then a rose-pink macular rash erupts on the trunk. What is the cause?
- Human herpesvirus 6 (Correct answer)
- Measles virus
- Group A Streptococcus
- Enterovirus
Correct answer: Human herpesvirus 6
Roseola infantum is caused by HHV-6 with high fever preceding the rash that appears after defervescence.
ABD Pediatric Dermatology 3
A 5-year-old presents with honey-colored crusted erosions around the nose and mouth.
What is the most common causative organism?