ABD Cutaneous Infectious Diseases 2

Question 1

A 6-year-old presents with honey-colored crusted lesions around the nose and mouth. What is the most likely diagnosis?

Accepted Answer

Non-bullous impetigo

Answer

Honey-colored crusts around the mouth and nose in a child are classic for non-bullous impetigo, usually caused by Staphylococcus aureus or Streptococcus pyogenes.

Question 2

Which organism is the most common cause of bullous impetigo?

Accepted Answer

Staphylococcus aureus

Answer

Bullous impetigo is caused by exfoliative toxin-producing Staphylococcus aureus, which cleaves desmoglein 1.

Question 3

A diabetic patient develops a rapidly spreading, exquisitely painful erythema with crepitus and dishwater-gray drainage. What is the priority intervention?

Accepted Answer

Urgent surgical debridement

Answer

Pain out of proportion, crepitus, and gray drainage suggest necrotizing fasciitis, a surgical emergency requiring immediate debridement.

Question 4

Erythrasma of the intertriginous areas fluoresces what color under Wood's lamp?

Accepted Answer

Coral-red

Answer

Corynebacterium minutissimum produces coproporphyrin III, causing coral-red fluorescence under Wood's lamp.

Question 5

A febrile patient has a sharply demarcated, raised, warm, erythematous plaque on the face. This presentation is most consistent with:

Accepted Answer

Erysipelas

Answer

Erysipelas involves the superficial dermis and lymphatics, producing a sharply demarcated, raised plaque, most often from Streptococcus pyogenes.

American Board of Dermatology (ABD) Practice Test

American Board of Dermatology (ABD) Practice Test

ABD Cutaneous Infectious Diseases 2