Dermatologist Certificate Pediatric and Special Population Dermatology 2 — Questions and Answers
Question 1: What is the pathognomonic skin finding of Kawasaki disease in children?
- Polymorphous exanthem with desquamation of fingertips in the recovery phase (Correct answer)
- Vesicular eruption on palms and soles
- Palpable purpura on the lower extremities
- Target lesions on the trunk and extremities
Correct answer: Polymorphous exanthem with desquamation of fingertips in the recovery phase
Kawasaki disease features a polymorphous rash plus desquamation of the fingertips and toes beginning in the periungual region during the subacute phase (10–25 days after fever onset).
Question 2: Xeroderma pigmentosum (XP) results from defects in which cellular repair mechanism?
- Nucleotide excision repair (NER) of UV-induced DNA damage (Correct answer)
- Mismatch repair
- Base excision repair
- Homologous recombination
Correct answer: Nucleotide excision repair (NER) of UV-induced DNA damage
XP is caused by inherited mutations in nucleotide excision repair genes, leaving UV-induced pyrimidine dimers unrepaired, leading to early and multiple skin cancers and photosensitivity.
Question 3: Which congenital melanocytic nevus size poses the greatest risk of malignant melanoma transformation?
- Giant CMN (>20 cm in adult equivalent size) (Correct answer)
- Small CMN (<1.5 cm)
- Medium CMN (1.5–19.9 cm)
- Speckled lentiginous nevus
Correct answer: Giant CMN (>20 cm in adult equivalent size)
Giant congenital melanocytic nevi (>20 cm) carry the highest lifetime risk of melanoma transformation (estimated 5–10%) and are also associated with neurocutaneous melanocytosis.
Question 4: Gianotti-Crosti syndrome (papular acrodermatitis of childhood) is most commonly associated with which viral infection?
- Epstein-Barr virus (EBV) (Correct answer)
- Hepatitis B virus
- Parvovirus B19
- Cytomegalovirus
Correct answer: Epstein-Barr virus (EBV)
While historically associated with hepatitis B, Gianotti-Crosti syndrome in the US is now most commonly triggered by EBV infection, presenting with papular eruption on the face and extremities.
Question 5: What is the recommended treatment for head lice (Pediculosis capitis) when permethrin 1% has failed?
- Oral ivermectin or topical spinosad/benzyl alcohol (Correct answer)
- Lindane shampoo
- Higher concentration permethrin
- Ketoconazole shampoo
Correct answer: Oral ivermectin or topical spinosad/benzyl alcohol
Resistance to permethrin is widespread; second-line options include oral ivermectin, topical spinosad (Natroba), or benzyl alcohol (Ulesfia), which work through different mechanisms.
Question 6: A teenager presents with grouped erythematous papules and nodules along the jawline and perioral area. Which hormonal influence is most implicated?
- Androgens stimulating sebaceous gland activity and sebum production (Correct answer)
- Estrogen dominance
- Elevated cortisol from stress
- Growth hormone
Correct answer: Androgens stimulating sebaceous gland activity and sebum production
Teenage acne along the jawline and lower face is driven by androgen-stimulated sebaceous gland hypertrophy and increased sebum production, particularly during puberty.
Dermatologist Certificate Pediatric and Special Population Dermatology 2
What is the pathognomonic skin finding of Kawasaki disease in children?