1.5 Infectious skin disorders

Question 1

what is it?

-red, tender, swollen rash with fever

Answer 1

cellulitis

Question 1

how to distinguish SSSS (Staphylococcal scalded skin syndrome) from TEN (toxic epidermal necrolysis)?

Answer 1

• histologically determined:
• SSSS: epidermolysis at stratum granulosum
• TEN: epidermolysis at E-D junction

Question 1

difference btwn cellulitis and erysipelas, clinical presentation

Answer 1

cellultis: diffuse inflammation
erysipelas: sharply outlined plaques

Question 1

What lab test to dx Herpes? and what to look for

Answer 1

Tzank test–rapid smear from freshly opened vesicle, use Giemsa stain.

• multinucleated keratinocytes with intranuclear inclusion bodies (‘Cowdry inclusions’). Looks like dark bodies surrounded by halo.
• typical of all HSV infected cells
• acantholysis of epidermis (breakage of keratinocytes)

Question 2

molluscum contagiosum

-people most commonly affected (3)

Answer 2

1. children
2. sexually active adults
3. immunocompromised

Question 3

what is it?

-small dome shaped, ‘crater-like’ nodules

Answer 3

molluscum contagiosum

Question 4

molluscum contagiosum

-histology

Answer 4

• purple inclusion bodies
• ‘Henderson-Patterson bodies”

Question 5

verruca: what do you see histologically?

Answer 5

• HPV infiltration of squamous keratinocyte (koilocytosis)
• see ‘hollow cells’ in epidermis (nuclear enlargement with surrounding halo)

Question 6

Erysipelas

Answer 6

• infection of upper dermis (as opposed to deep dermis of cellulitis)
• sharply outlined erythematous, edematous plaques

Question 7

Verruca

Answer 7

(wart)

• flesh-colored papule, rough surface
• hands, feet
• HPV infection of keratinocytes

Question 9

cellulitis

• what is it
• clinical findings

Answer 9

• infection of dermis (deeper than impetigo)
• usu S. Aureus, S. pyogenes
• red, tender, swollen rash with fever

Question 10

how to dx dermatophytoses?

Answer 10

KOH stain, rapid test to see branching hyphae

Question 12

what is it?

erythematous macules that progress to pustules, rupture results in ‘honey colored crust’

Answer 12

impetigo

Question 14

impetigo

• what is it
• clinical findings

Answer 14

• superficial bacterial skin infection, usu S. Aureus, S. pyogenes
• erythematous macules that progress to pustules, rupture results in ‘honey colored crust’

Question 15

what is it?

• flesh-colored papule, rough surface
• hands, feet

Answer 15

verruca (wart)

Question 16

molluscum contagiosum

• clinical finding
• what microbe

Answer 16

• small dome shaped, ‘crater-like’ nodules
• poxvirus

Question 17

natural history of verruca

Answer 17

• usually self-limiting
• regress spontaneously from 6 months to 3 years.

Question 18

staphylococcal scalded skin syndrome

• clinical finding
• what layer is destroyed?

Answer 18

• sloughing of skin with erythematous rash and fever.
• epidermolysis of stratum granulosum
• S. Aureus exfoliative toxins A and B

Question 19

varicella

• how does rash present?
• how does infection spread

Answer 19

‘chickenpox’

• rash progresses from macules to vesicles to pustules (all stages simultaneously present, very characteristic)
• infection spread respiratory route, 2 week incubation

Question 20

cellulitis:

• common risk factors
• what should you worry about its progression?

Answer 20

• recent surgery, trauma, insect bite
• can progress to necrotizing fasciitis (anaerobic flesh eating bacteria)

Question 21

Condyloma accuminatum:

• common types
• high risk types

Answer 21

1. common: HPV 6, 11 (90% of all)
2. high risk to cancer: 16, 18, 31, 33 (think jets)

Question 22

what is it?

• red, tender swollen rash with fever
• presence of crepitus

Answer 22

• necrotizing fasciitis
• crepitus from CO2 production of anaerobic flesh eating bacteria