MS - Path (Infectious & Blistering skin disorders)

Question 1

Give 5 examples of infectious skin disorders.

Answer 1

(1) Impetigo (2) Cellulitis (3) Necrotizing fasciitis (4) Staphylococcal scalded skin syndrome (5) Hairy leukoplakia

Question 2

What is the extent of impetigo in the skin? How does it usually appear?

Answer 2

Very superficial skin infection; Honey-colored crusting

Question 3

What pathogens usually cause impetigo? How contagious it it?

Answer 3

Usually from S. aureus or S. pyogenes

Question 4

What pathogen usually causes bullous impetigo, and how does it appear?

Answer 4

Bullous impetigo has bullae and is usually caused by S. aureus.

Question 5

Describe cellulitis.

Answer 5

Acute, painful, spreading infection of dermis and subcutaneous tissues

Question 6

What 2 pathogens usually causes cellulitis?

Answer 6

Usually from S. pyogenes or S. aureus

Question 7

How does cellulitis often start?

Answer 7

Often starts with a break in skin from trauma or another infection

Question 8

What kind of injury does necrotizing fasciitis cause (in reference to impetigo/cellulitis), and what pathogens usually cause it?

Answer 8

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

Question 9

What physical findings characterize necrotizing fasciitis, and why causes them?

Answer 9

Results in crepitus from methane and CO2 production. “Flesh-eating bacteria” Causes bullae and a purple color to the skin

Question 10

What is the pathophysiology of Staphylococcal scalded skin syndrome? From what other disorder must this be distinguished, and how?

Answer 10

Exotoxin destroys keratinocyte attachments in the stratum granulosum only (vs. toxic epidermal necrolysis, which destroys the epidermal-dermal junction).

Question 11

What signs/symptoms characterize the presentation of staphylococcal scalded skin syndrome?

Answer 11

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

Question 12

In what 2 patient populations is staphylococcal scalded skin syndrome seen?

Answer 12

Seen in newborns and children

Question 13

What defines hairy leukoplakia?

Answer 13

White, painless plaques on the tongue that cannot be scraped off

Question 14

What pathogen mediates hairy leukoplakia?

Answer 14

EBV mediated

Question 15

In what patient population does hairy leukoplakia occur?

Answer 15

Occurs in HIV-positive patients

Question 16

Name 5 blistering skin disorders.

Answer 16

(1) Pemphigus vulgaris (2) Bullous pemphigoid (3) Dermatitis herpetiformis (4) Erythema multiforme (5) Stevens-Johnson syndrome

Question 17

What defines pemphigus vulgaris?

Answer 17

Potentially fatal autoimmune skin disorder with IgG antibody against desmoglein (component of desmosomes)

Question 18

What are the 2 significant physical findings of pemphigus vulgaris? What is the major pathophysiology behind them?

Answer 18

(1) Flaccid intraepidermal bullae caused by acantholysis (keratinocytes in stratum spinosum are connected by desmosomes); (2) oral mucosa are involved.

Question 19

Describe the key immunofluorescence finding of pemphigus vulgaris.

Answer 19

Immunofluorescence reveals antibodies around epidermal cells in a reticular (net-like) pattern

Question 20

What clinical sign characterizes pemphigus vulgaris, and what defines it?

Answer 20

Nikolsky sign (+) (separation of epidermis upon manual stroking of skin)

Question 21

How does bullous pemphigoid compare to pemphigus vulgaris?

Answer 21

Less severe than pemphigus vulgaris

Question 22

What defines bullous pemphigoid?

Answer 22

Involves IgG antibody against hemidesmosomes (epidermal basement membrane; Think: “antibodies are ‘BULLOW’ the epidermis)

Question 23

What physical finding(s) characterize bullous pemphigoid, especially to distinguish it from pemphigus vulgaris?

Answer 23

Tense blisters containing eosinophils affect skin but spare oral mucosa; Nikolsky sign (-) (unlike pemphigus vulgaris, which involves oral mucosa and is Nikolsky sign (+))

Question 24

What immunofluorescence finding characterizes bullous pemphigoid?

Answer 24

Immunofluorescence reveals linear pattern at epidermal-dermal junction

Question 25

What are 3 characteristic physical findings associated with dermatitis herpetiformis, and where on the body are they often found?

Answer 25

Pruritic papules, vesicles, and bullae (often found on elbows)

Question 26

What is the pathophysiology behind dermatitis herpetiformis?

Answer 26

Deposits of IgA at the tips of dermal papillae

Question 27

With what condition is dermatitis herpetiformis associated?

Answer 27

Associated with celiac disease

Question 28

What are 4 associations to make with erythema multiforme?

Answer 28

Associated with infections (e.g., Mycoplasma pneumoniae, HSV), drugs (e.g., sulfa drugs, Beta-lactams, phenytoin), cancers, and autoimmune disease

Question 29

Give 2 examples of infections that may be associated with erythema multiforme.

Answer 29

Infections (e.g., Mycoplasma pneumoniae, HSV)

Question 30

Give 3 examples of drugs that may be associated with erythema multiforme.

Answer 30

Drugs (e.g., sulfa drugs, Beta-lactams, phenytoin)

Question 31

Describe the presentation of erythema multiforme.

Answer 31

Presents with multiple types of lesions - macules, papules, vesicles, and target lesions (look like targets with multiple rings and a dusky center showing epithelial disruption)

Question 32

Although erythema multiforme may present with multiple types of lesions, what is a characteristic lesion? Describe that lesion.

Answer 32

Target lesions (look like targets with multiple rings and a dusky center showing epithelial disruption)

Question 33

What physical findings and major complication/concern characterizes Stevens-Johnson syndrome?

Answer 33

Characterized by fever, bulla formation, and necrosis, sloughing of skin, and a high mortality rate.

Question 34

What, and how many, structures are sually involved in Stevens-Johnson syndrome? How may the skin lesion appear, and to what other condition is this comparable?

Answer 34

Typically 2 mucous membranes are involved, and skin lesions may appear like targets as seen in erythema multiforme

Question 35

What defines toxic epidermal necrolysis?

Answer 35

A more severe form of Stevens-Johnson syndrome with > 30% of the body surface area involved is toxic epidermal necrolysis

Question 36

What are 2 physical findings that may be seen in toxic epidermal necrolysis patients?

Answer 36

(1) Large bullae with skin sloughing in sheets (2) Epidermal sloughing of skin leading to depigmentation