Viral Skin Infections Flashcards
Descibre HSV
dsDNA virus that is contracted via direct contact (skin to skin) that results in primary infection 3-7 days after exposure and then the virus spread via sensory nerves to ganglia where latent infection develops and is characterized by recurrences associated with viral shedding
What are some triggers of recurrent herpes?
These tend to be milder (primary may have malaise, LAD, fever) and are triggered by fever, sun exposure, and stress
Classic description of herpes
clusters of monomorphous vesicles with an eryhtematous base that look alike, and over time these vesicles rupture producting ‘punched-out” erosions that crust
How can herpes be confirmed?
Tzanck smear- scrap an open vesicle from the base of a lesion (positive with see multinucleated giant cells)
- Viral culture (positive within 24-48 hrs)
- PCR
What are other things on the DDx for herpes?
- impetigo (caused by strep or staph aureus)
- aphthous stomatitis
- syphilitic chancre
How is herpes treated?
Mild: topical antiviral
Moderate to Severe: systemic antiviral (oral or IV)
What is varicella zoster virus (VZV)?
Causes shingles (herpes zoster) that is a problem of reactivation of latent VZV (20-30% of lifetime risk that increases with age and especially after age 60)
Describe VZV
dsDNA that remains latent in dorsal root ganglia and reactivation (shingles) is triggered by trauma, stress, fever, radiation, or immunosuppression
common is you’ve had chicken pox OR the vaccine
How does VZV present?
prodrome syndromes of pain, pruritus, burning with grouped vesicles that present over a single dermatome (trunk most common)
What are some more rare places for reactivation of VZV to occur?
- Trigeminal nerve (V1, ophthalmic) in 10-15% of cases or a Hutchinson’s sign, which is vesicles presenting at the tip/nose from nasociliary branch involvement of the trigeminal nerve and can lead to blindess and is typically the most painful
- V2/V3 distribution (can lead to facial palsy that can be longlasting or vertigo, deafness if the ear is invovled)
Progession of VZV?
rash typically resolves within 3-5 weeks but can see postherpetic neuralgia in 5-20% of patients (typically over 40 yo) that is characterized by lingering pain
How is VZV diagnosed?
- Tzanch smear
- Viral culture (VZV is more difficult to culture than herpes simplex)
- PCR
How is shingles treated?
typically oral antiviral (within 72 hrs!) and pain meds
Shingled vaccine
Zostavax- recommended for pts. 60+ and decreases risk of shignled by 51% and neuralgia by 67%
What is Molluscum Contagiosum?
cutaneous infection caused by Pox virus (dsDNA) that is contracted via skin to skin, fomites (sharing towels), or autoinoculation (picking, scratching) and tends to resolve spontaneously within months to years but may leave a depressed scar
How does MC look?
pink to skin-colored 2-10mm dome-shaped waxy papules that may or may not have a central umbilication (divet)
these can get very red, swollen, and sore- good sign that they are getting ready to go away
This is the body reacting and is a good sign
What are the most effective treatments for MC?
Numerous methods but no clear evidence to suport any of them
Treatment options for MC?
- nonintervention (will go away eventually)
- Physical removal (curettage, cryotherapy, cantharidin)
- Local irriation (topical retinoids, keratolytics)
- Immunomodulators
What are some immune modulators used in MC?
Topical: Imiquimoid
Systemic: Cimetidine
What is Cantharidin?
Chemical vesicant (causes a blister) used to treat molluscum and warts)- 90% cleared after 2 applications (not typically used on genitalia or face)
AEs: blistering, pain, erythema
What causes warts (verrucae)?
HPV (dsDNA, over 100 types)
Where can warts happen?
anywhere! These are benign and will generally involute within 2 yrs but they can be painful and embarrassing
What are the oncogenic strains of HPV?
16, 18, 31, 33
How are warts contracted?
- Direct (hetero or autoinoculation)
- Indirect (fomites-towels or warm, moist surfaces)
Progression of warts?
enter through a small (or large) area of traumatized skin and have an incubation period of 1-6 months. 2/3rds resolve within 2 yrs mostly via cell-mediated immunity
Types of Warts
-Verrucae Vulgaris (common warts)
Verrucae Plantaris
Verrucae Plana (flat warts)
Condylomata cuminate (anogenital warts)
Describe common warts
Mostly occur on the hands (can be periungual/subungal- cant burn/freeze) but can occur anywhere including the oral mucosa and can be single/multiple.
These typically present with disruption of normal skin lines and paring the surface reveals “black dots’ (aka seeds0
These tend to respond well to cryotherapy
Describe flat warts
Can occur anywhere but most commonly in face, neck, arms, and legs and are described as smooth, skin-colored to slightly tan/pink flat-topped thin papules (3-5mm) and/or plaques
NOTE: shaving over these surfaces can facilitate spread
When they grow together= mosaic warts
Corns are not common in children and have a more indurated center
How can anogenital warts be contracted?
- sexual contact
- vertical (perinatal)
- benign (nonsexual) heteroinoculation or autoinoculaiton
- fomite (e.g. towels)
Describe anogenital warts
skin-colored to pnk/tan soft papules (1-5mm) usually multiple in number (and can form large masses) that are usually asymptomatic (but irriation may cause pain, bleeding)
How are anogenital warts treated?
No specific antiviral therapy for HPV infections, and there are many trewatments but none are great.
Two main categories: Destructive (physical/chemical or immunomodulatory)
HPV Vaccines?
Gardasil (16, 18, 6, 11)
Cervarix (16, and 18)
What are some indications to treat warts?
indicated in painful, extensive, enlarging, subject to trauma, or cosmetically objectionable and the choice of tx depends on multiple factors including age, number, size, location, etc.
