MS - Path (Infectious & Blistering skin disorders) Flashcards
Pg. 433-435 in First Aid 2014 Sections include: -Infectious skin disorders -Blistering skin disorders
Give 5 examples of infectious skin disorders.
(1) Impetigo (2) Cellulitis (3) Necrotizing fasciitis (4) Staphylococcal scalded skin syndrome (5) Hairy leukoplakia
What is the extent of impetigo in the skin? How does it usually appear?
Very superficial skin infection; Honey-colored crusting
What pathogens usually cause impetigo? How contagious it it?
Usually from S. aureus or S. pyogenes
What pathogen usually causes bullous impetigo, and how does it appear?
Bullous impetigo has bullae and is usually caused by S. aureus.
Describe cellulitis.
Acute, painful, spreading infection of dermis and subcutaneous tissues
What 2 pathogens usually causes cellulitis?
Usually from S. pyogenes or S. aureus
How does cellulitis often start?
Often starts with a break in skin from trauma or another infection
What kind of injury does necrotizing fasciitis cause (in reference to impetigo/cellulitis), and what pathogens usually cause it?
Deeper tissue injury, usually from anaerobic bacteria or S. pyogenes
What physical findings characterize necrotizing fasciitis, and why causes them?
Results in crepitus from methane and CO2 production. “Flesh-eating bacteria” Causes bullae and a purple color to the skin
What is the pathophysiology of Staphylococcal scalded skin syndrome? From what other disorder must this be distinguished, and how?
Exotoxin destroys keratinocyte attachments in the stratum granulosum only (vs. toxic epidermal necrolysis, which destroys the epidermal-dermal junction).
What signs/symptoms characterize the presentation of staphylococcal scalded skin syndrome?
Characterized by fever and generalized erythematous rash with sloughing of the upper layers of epidermis that heals completely
In what 2 patient populations is staphylococcal scalded skin syndrome seen?
Seen in newborns and children
What defines hairy leukoplakia?
White, painless plaques on the tongue that cannot be scraped off
What pathogen mediates hairy leukoplakia?
EBV mediated
In what patient population does hairy leukoplakia occur?
Occurs in HIV-positive patients
Name 5 blistering skin disorders.
(1) Pemphigus vulgaris (2) Bullous pemphigoid (3) Dermatitis herpetiformis (4) Erythema multiforme (5) Stevens-Johnson syndrome
What defines pemphigus vulgaris?
Potentially fatal autoimmune skin disorder with IgG antibody against desmoglein (component of desmosomes)
What are the 2 significant physical findings of pemphigus vulgaris? What is the major pathophysiology behind them?
(1) Flaccid intraepidermal bullae caused by acantholysis (keratinocytes in stratum spinosum are connected by desmosomes); (2) oral mucosa are involved.
Describe the key immunofluorescence finding of pemphigus vulgaris.
Immunofluorescence reveals antibodies around epidermal cells in a reticular (net-like) pattern
What clinical sign characterizes pemphigus vulgaris, and what defines it?
Nikolsky sign (+) (separation of epidermis upon manual stroking of skin)
How does bullous pemphigoid compare to pemphigus vulgaris?
Less severe than pemphigus vulgaris
What defines bullous pemphigoid?
Involves IgG antibody against hemidesmosomes (epidermal basement membrane; Think: “antibodies are ‘BULLOW’ the epidermis)
What physical finding(s) characterize bullous pemphigoid, especially to distinguish it from pemphigus vulgaris?
Tense blisters containing eosinophils affect skin but spare oral mucosa; Nikolsky sign (-) (unlike pemphigus vulgaris, which involves oral mucosa and is Nikolsky sign (+))
What immunofluorescence finding characterizes bullous pemphigoid?
Immunofluorescence reveals linear pattern at epidermal-dermal junction
What are 3 characteristic physical findings associated with dermatitis herpetiformis, and where on the body are they often found?
Pruritic papules, vesicles, and bullae (often found on elbows)
What is the pathophysiology behind dermatitis herpetiformis?
Deposits of IgA at the tips of dermal papillae
With what condition is dermatitis herpetiformis associated?
Associated with celiac disease
What are 4 associations to make with erythema multiforme?
Associated with infections (e.g., Mycoplasma pneumoniae, HSV), drugs (e.g., sulfa drugs, Beta-lactams, phenytoin), cancers, and autoimmune disease
Give 2 examples of infections that may be associated with erythema multiforme.
Infections (e.g., Mycoplasma pneumoniae, HSV)
Give 3 examples of drugs that may be associated with erythema multiforme.
Drugs (e.g., sulfa drugs, Beta-lactams, phenytoin)
Describe the presentation of erythema multiforme.
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)
Although erythema multiforme may present with multiple types of lesions, what is a characteristic lesion? Describe that lesion.
Target lesions (look like targets with multiple rings and a dusky center showing epithelial disruption)
What physical findings and major complication/concern characterizes Stevens-Johnson syndrome?
Characterized by fever, bulla formation, and necrosis, sloughing of skin, and a high mortality rate.
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?
Typically 2 mucous membranes are involved, and skin lesions may appear like targets as seen in erythema multiforme
What defines toxic epidermal necrolysis?
A more severe form of Stevens-Johnson syndrome with > 30% of the body surface area involved is toxic epidermal necrolysis
What are 2 physical findings that may be seen in toxic epidermal necrolysis patients?
(1) Large bullae with skin sloughing in sheets (2) Epidermal sloughing of skin leading to depigmentation
