Lec48 Infectious disease of skin Flashcards
What causes warts?
HPV
What types of dermo findings for HPV1 and 2?
- palmoplantar [palms and soles] and common warts
What type of dermo findings for HPV6 and 11?
- genital warts
What are effects of HPV16/18?
cervical/genital cancer
What is pathogenesis of HPV infection?
- spread by direct contact with broken skin –> virus enters basal –> induces cellular proliferation
What is appearance of HPV warts?
- verrucuous papule/plaque with thrombosed capillaries
- thrombosed capillaries show as black dots
- elevated, rough skin
How do you distinguish corn/callous from wart?
wart ablates skin lines
corn/callous does not
What is typical therapy for warts?
- mechanical destruction –> cryotherapy [freezing] or salicylic acid plasters
- induce immune response: inject candida to cause local immune response
What is sign of HSV derm?
crop of vesicles on erythematous base
Which type of herpes primarily responsible for labial herpes? genital herpes?
HSV1 = labial [lips] HSV2 = genital
What is pathogenesis of HSV? transmission?
- virus contacts skin –> replicates in dermis/erpidermis –> infects and latent in trigeminal or sacral sensory ganglion –> recurs focally where nerve innervates
transmission by direct contact –> contagious until crusted
What triggers HSV reinfection?
stress, UV light, fever
What is manifestation of HSV prodrome?
tenderness/burning –> then skin pressentation/blister
What happens if HSV near eye?
can lead to eye infection –> keratitis/blindness
When do you get eczema herpeticum?
- spreads along contiguous skin due to compromised barrier [eczema, burn, etc]
What is disseminated HSV? who gets it?
- spreads more widely than one area, can have more scattered individual lesions
- occurs in immunocompromised
Where does ZVZ stay latent?
sensory nerve root
What is life cycle involved in shingles? clinical signs?
- dermatomal rash, does not cross midline [vs HSV crosses midline]
- can have post-herpetic nerualgia in affected sensory nerve
- lytic life cycle
Who gets disseminated VZV? sign?
- in immunocompromised
- have dermatomal rash + individual lesions via hematogenous spread
How is VZV transmitted?
- contagious –> by contact
How do you diagnose HSV/VZV?
- tzanck spear [only tells you part of herpes family]
- DFA –> anti HSV/VZV antibodies
- viral culture
- PCR
What is treatment for HSV/VZV?
- acyclovir, valganciclovir, famciclovir
- foscarnet [for resistant]
What can cause mononucleosis?
- usually EBV [human herpesvirus 4]
- also could be CMV, toxoplasmosis rarely
What are clinical features of infectious mono?
- triad: pharyngitis, fever, lymphadenopathy [esp cervical]
- periorbital edema
- hepatosplenomegaly
- can have rash beginning on trunk with later extension to face
- 90% have hypersensitivity skin rxn to ampicillin/amoxicillin
How do you diagnose mono?
- > 50% lymphocytes, > 10% LFTs
- monospot test: detects IgM antibodies in wk 2]
How do you treat mono?
- coritcosteroid in case of complications
- otherwise supportive
What causes erythema infectiosum? Other names?
other names: fifth disease, slapped cheek disease
- due to human parvovirus B19
What type of properties human parvovirus B19 [strandedness, DNA or RNA]?
- single strand
- DNA
What are clinical features of erythema infectiosum?
- prodrome: fever, headache, myalgia
- exanthem: bright red macular erythema [= bright red patches esp on face]
- may have arthralgia or arthritis
What is pathogenesis of erythema infectiosum?
- initially infect respiratory –> B19 viremia with decrease in reticulocytes –> viremia ends with IgM Ab –> IgG appears with rash and arthralgia after a few days
What clinical disorders associated with parvovirus B19?
- erythema infectiosum
- adults: arthropathy: may be without exanthem
- aplastic anemia [in sickle cell pts] –> ab pain, resp symptoms
- paupular purpuric gloves and socks syndrome [purpura on hands and feet and oral mucosa]
What are outcomes of congenital parvovirus B19 infection? when is infection the greatest risk?
greatest risk = first 20 wks gestation
effects: fetal hydrops, intreuterine demise, still birth
How do you diagnose parvovirus B19?
- serology [anti B19 IgM Ab]
- PCR
What is treatment for parvovirus B19?
- no specific antiviral treat
- symptomatic support
How is measles transmitted?
respiratory droplets
What are clinical features of measles:
prodrome: fever, cough, koplik spots, nasal congestion
exanthem: erythematous macules and papules begin on face and move down = irregulary shaped bright red spots with blueish white central dot
What are possible complications of measles?
- pneumonia, encephalitis, subacute sclerosing panencephalitis
What causes molluscum contagiosum?
poxvirus
What is mech of molluscum contagiosum transmission?
- by direct contact
- in adults –> sexually transmitted
- in children see it with atopic diathesis
What is the appearance of molluscum contagiosum?
umbilicated papule
What is treatment for mollscum contagiosum?
- self limited, can scrape off but may leave scar
What are the 3 superficial fungal infections of the skin?
- dermatophytes
- candida
- pityriasis [tinea] versicolor
What organisms cause dermatophytes?
most common: trichophyton rubrum
also: microsporum canis and T. tonsurans
What types of lesions are dermatophyte lesions?
pruritic
How do you diagnose dermatophytes?
KOH [potassium hydroxide] and/or culture
What is another name of tinea corporis?
ring worm
What is tinea capitis?
- dermatophyte of head
- fungus invades hair follicle and shaft
Is tinea capitis contagious? How is it spread?
- it is contagious
- spread by sharing hats, bedding
- pets can be a source
What are three types of tinea capitis?
black dot tinea capitis = hair break near scalp looks like black dots
kerion = boggy inflammatory plaque, inflammatory red
favus = extensive hairloss with scarring and hyperkeratotic yellow crusts called scutula, most severe type
What is manifestation of tinea corporis?
round red rash
What is favus?
type of tinea capitis = extensive hairloss with scarring and hyperkeratotic yellow crusts called scutula
What is kerion?
type of tinea capitis = boggy inflammatory plaque
What is tinea unguium?
dermatophyte infection of nail
What is appearance of tinea unguium?
yellow discoloration of nail
dystrophy
What is treatment for dermatophytes?
topical: terbinafine best, others [ketoconazole, clotrimazole, econazole]
oral: terminafine or itraconazole
What is appearance of tinea cruris?
- aka jock itch
- red paches, may have pustule at border
- spares the scrotum [vs candidal intergrigo affects scrotum
- no satellite lesions
What is different tinea cruris and candidal intertrigo
- tinea spares the scrotum [vs candidal intergrigo affects scrotum]
- tinea has no satellite lesions [vs candida does]
How do you treat tinea capitis?
- oral a
What is side effect of terbinafine?
possible hepatotoxicity
Which dermatophytes can you treat topically?
with limited area [groin, small area body]
tinea capitis –> use shampoo
Which dermatophytes do you treat orally?
- tinea unguium
- tinea capitis
What is sign of oral candidiasis?
- creamy white cottage cheese like plaques that are easily scraped off [pseudomembrane]
- burning, pain, pruritis [itching]
Where do you get oral candidiasis lesions?
- dorsal tongue
- buccal mucosae
- palate
- pharynx
How do you get oral candidiasis?
- inhaled steroids for asthma
- immunocompromised [HIV]
What is treatment for oral candidiasis?
- fluconazole, clotrimazole or nystatin
Where do you get candidal intertrigo?
any skin folds, also get satellite lesions
How do you prevent candidal diaper dermatitis?
- barrier cream after diaper change –> irritant feces and urine contact cream not skin
How do you treat candidal diaper dermatitis?
- oral antifungals –> candida can colonize gut
What are risk factors for candidal angular chelitis?
- chronic lip licking, drooling
How do you get candidal paronychia / what is it?
cuticle gets inflamed from chronic water exposure
What are signs of systemic candidiasis [candidemia]?
- generalized papules and pustules
- neutropenia
What causes tinea [pityriasis] versicolor?
pityrosporum orbiluare
What are signs of tinea versicolor?
- hyper and hypopigmented pathces with fine scale on chest and back
- can be asymptomatic
How do you diagnose tinea versicolor?
- clinical inspection
- KOH scraping –> shows spaghetti and meatballs [hyphae and spores]
What is treatment for tinea versicolor?
- ketoconazole, keratolytics
Who gets deep [invasive] fungal skin infections? How do they usually appear?
- seen in immunocompromised
- usually ulcerated plaques or disseminated papules
