PATH - Skin Infections

Question 1

Impetigo

Answer 1

Very superficial skin infection.
Highly contagious.

Usually from *S aureus or *S pyogenes.

• Honey-colored crusting
• Bullous impetigo has bullae and is usually caused by S aureus

Question 2

Erysipelas

Answer 2

Infection involving *upper dermis and *superficial lymphatics

usually from *S pyogenes.

Presents with well-defined demarcation between infected and normal skin

Question 3

Cellulitis

Answer 3

Acute, painful, spreading infection of *deeper dermis and subcutaneous tissues.

Usually from *S pyogenes or *S aureus

Question 4

Abscess

Answer 4

Collection of pus from a *walled-off infection within *deeper layers of skin

Offending organism is
almost always *S aureus

Question 5

Necrotizing fasciitis

Answer 5

Deeper tissue injury, usually from anaerobic bacteria or *S pyogenes

Results in *crepitus from
methane and CO2 production.

Causes bullae and a purple color to theskin

Question 6

Staphylococcal scalded skin syndrome

Answer 6

Exotoxin destroys keratinocyte attachments in *stratum granulosum only

Characterized by fever and generalized erythematous rash with sloughing of the *upper layers of the epidermis that heals completely

⊕ Nikolsky sign

Question 7

Herpes

Answer 7

Herpes virus infections (HSV1 and HSV2) of skin can occur anywhere from mucosal surfaces to normal skin

These include herpes labialis, herpes genitalis, herpetic whitlow (finger).

Question 8

Molluscum contagiosum

Answer 8

Umbilicated papules caused by a *poxvirus.

While frequently seen in children, it may be sexually
transmitted in adults

Question 9

Varicella zoster virus

Answer 9

Causes varicella (chickenpox) and zoster (shingles).

Varicella presents with multiple crops of lesions in *various stages from vesicles to crusts.

Zoster is a reactivation of the virus in dermatomal
distribution (unless it is disseminated).

Question 10

Hairy leukoplakia

Answer 10

Irregular, white, painless plaques on lateral tongue that *cannot be scraped off

*EBV mediated