091914 infections Flashcards
impetigo
common superficial bacterial infection
most common in kids
highly infectious (direct contact)
Staph aureus (less commonly Strep pyogenes)
small vesicles that burst, replaced by thick yellowsih crust that is honey colored
mouth, nose, extremities
bullous impetigo
blisters because the connections btwn keratinocytes are destroyed
histology of impetigo
crust right at stratum corneum-will see serum and neutrophils
staphlylococcal scalded skin syndrome
infant and children
toxin mediated type of exfoliative dermatitis
toxigenic strains of Staph aureus
two exotoxins (epidermolytic toxin A and epidermolytic toxin B)
causes intraepidermal splitting through granular layer. large, flaccid bullae
SSSS occurs where
face
neck
trunk (includes axillae and groins)
what is important to remember about where SSSS doesn’t involve?
doesn’t involve mucous membranes
difference btwn kids and adults in terms of SSSS?
in adults, a septicemia may ensue
cellulitis
deep pyogenic infection
diffuse inflam of connective tissue of skin and, or the deeper soft tissues/fat
expanding area of erythema
beta hemolytic strep, coagulase positive staph, other organisms
where is cellulitis more common
legs
erysipelas
distinctive type of cellulitis-upper dermis
bacterial skin infection involving upper dermis (superficial cutaneous lympathics)
prevalent in elderly
s pyogenes is most common causative agent
what does erysipelas look like clinically
sharply outlined edema erythematous tender painful plaque
histology of erysipelas
lot of white space due to fluid in dermis
increased amt of neutrophils
verrucae
warts
HPV (most caused by low risk HPV)
verruca vulgaris (anywhere, commonly on hands), plantar warts, anogenital warts
regress spontaneously
histology of verrucae
papillomatous, hyperplasia of epidermis. filiform
prominent granular cell layer (has enlarged clumps of irregular basophilic keratohyaline granules)
large cells with prominent vacuolated cytoplasm(koilocytosis) and small nucleus are seen in upper layers of epidermis
condyloma accuminatum
wart on genital areas
caused by HPV 6 and 11
cauliflower lesions with stalk
acanthosis
diffuse epidermial hyperplasia
HSV lesions look like
clear vesicles, heal w/o scar
what lesions are usually seen with varicella?
lesions develop in successive crops, so rash usually has pocks at different stages of development (papules, vesicles, pustules, crusted lesions, healing lesions)
herpes zoster presents usually in what regions of the body
thoracic or lumbar, or facial
histophatology of herpes zoster vs herpes simplex
virtually indistinguishable
how does varicella spread
respiratory
histopathology of HSV
epidermal acantholysis
several multinucleated keratinocytes with glassy intranuclear inclusions (Cowdry type A) and ballooning degeneration
tzank smear
fast cytological diagnosis
make a smear from the base of a freshly opened vesicle and stain it with Giemsa stain
not as sensitive
for testing to see if it’s herpes
moluscum contagiosum
cuteaneous infection
caused by brick shaped DNA poxvirus
transmitted by direct skin contact btwn children
solitary or multiple dome shaped, UMBILICATED, waxy papules
in adults, can be sign of sexual transmission or immunosuppression
histoly of molluscum contagiosum
inverted lobules of acanthotic and hyperplastic epidermis
eosinophilic inclusion bodies in the cytoplasm of keraticnocytes just above basal lyaer (Henderson Patterson or molluscum bodies)
scabies
caused by mite Sarcoptes scabiei acquired through close contact hands and feet, penis extremely pruritic papulovesicular
histology of scabies
eggs in burrows in epidermis-stratum corneum
dermatophytoses
group of related fungi
invade keratinized tissues
cause ringworm/tinea
epidermophyton, microsporum, trichophyton
clinical appearances are quite variable-scaly erythematous plaques, often annular
epidermophyton invades what
epidermal keratin
microsporum and trichophyton invade what?
epidermal keratin and also hair
tinea capitis
scaly patches on scalp
tinea corporis
scaly, annular, erythematous patches on body
tinea manuum and pedis
erythema and scale of hands or feet
tinea cruris
erythematous, macerated patches of groin
tinea unguium (onchomycosis)
thickened yellow nails
histology of dermatophyte infec
wide range of changes, including: presence of neutrophils sandwich sign (hyphae in btwn normal stratum corneum and lower layer of stratum ocrneum with either orthokeratotic or parakeratosis)
PAS stain can reveal fungus
KOH prep rapid test
can find branching hyphae of fungal infec
tinea versicolor
worldwide but more common in tropical climates
majority caused by yeast Malassezia globosa
clinical pres: multiple irregular areas of hypo or hyperpigmentation, which are circular and macular, may become confluent
histology of tinea versicolor
stratum cornuem has round budding yeasts and short septated hyphae–sphagetti and meatballs. clearly seen in H & E
