Viral Skin Infections Flashcards
Clinical features of common warts (verrucae vulgaris)
-Typically acral in distribution, most commonly seen in children and particular HPV types are common.
-The hyperkeratotic papules or nodules, when pared back with a blade, show point-like dermal vessels (black specks)
-In flexures, they may be more papillomatous
-On the feet, verrucae plantaris (still just a common wart) can cause more problems because of pressure forcing them inwards, and hence causing pain
-Viral warts are a particular problem in individuals who are immunosuppressed, as they are much more common, often larger, and can easily be confused with skin cancers in this high risk skin cancer group.
What are plane warts?
-HPV infections, which are commonly seen on the back of the hands or the face, as tiny little flat topped papules which often markedly pigment after sun exposure
What is the treatment for HPV warts?
-Salicylic acid preparations and paring (with a blade), which removes hyperkeratotic areas, with or without cryotherapy; or cryotherapy alone.
-Curettage and electro-desiccation, or application of contact sensitisers, or lasers.
Overview of Molluscum Contagiosum
-Pox virus infection spread by direct contact.
-Most common in children on the trunk.
-If you see it in adults, think about a cause of immunosuppression, including HIV.
-The lesion, papules, or nodules have a characteristic shiny white centre, and central umbilication.
-In childhood they are often accompanied by eczema around the lesions and they frequently bleed due to excoriation.
-If a child in a family has them, they should use a separate towel to the other children.
-They can persist for up to 6 months or more before immunity develops, and parents (perhaps) reasonably demand action, when only inaction is best for the child, as we have no cure.
Describe primary herpes ginvio-stomatitis
-Occurs in a large proportion of young children producing oral ulcers and blisters, and variable systemic disturbance.
-The virus is not cleared in the majority of individuals and is latent; reactivation of the virus leads to the clinical features of herpes simplex labialis (cold sores).
-Up to a third of the world’s population have had a symptomatic herpes infection
-Treated by Aciclovir to shorten duration of illness if used from earliest onset of symptoms
Clinical features of reactivation of simplex
- a tingling sensation
- papule formation
- clustering, or grouping, of lesions
- blister formation
=Recurrence precipitated by UVR exposure/ other illnesses (fever blisters)
Overview of eczema herpeticum
-Most commonly in children with atopic dermatitis who develop hundreds, or thousands, of punched out ulcerated lesions (monomorphic)
-Children become sick and prior to the advent of modern antivirals the condition frequently proved fatal, progressing to pneumonia or herpes encephalitis.
-Diagnosis depends on awareness, as often the herpetic lesions are subtle, and misdiagnosed as impetiginized eczema
-Rapid fluorescence based diagnosis is possible on skin scrapings, as is PCR diagnosis.
-Treatment is with systemic antivirals (e.g. Aciclovir family — not topical antivirals)
Describe Herpes Neonatorum
-Primary infection with Herpes simplex, usually acquired from a HSV positive mother during childbirth.
-Active genital herpes at the time of delivery is a clear risk to the foetus and is an indication for Caesarean section
Describe chickenpox
-90% of the population will have had chicken pox before the mid-teenage years
- Infection is spread via droplets, with an incubation period of up to 3 weeks
- Lesions start off as red macules, before forming small blisters, with or without pus, which then crust
- In chicken pox, the lesions occur in crops so that at any one time they are at different stages of evolution
- The lesions tend to itch and end up being scratched – this is often a major problem, as some lesions heal leaving punched out (depressed) scars.
- Following primary infection, latent virus remains in the dorsal root ganglion. In adults, varicella infection is more problematic. In adults without previous infection, or who are immunocompromised, varicella can produce a severe illness with pyrexia, malaise, and potentially fatal varicella pneumonia
What happens in primary varicella infections in pregnancy?
-First trimester there is a recognised constellation of foetal abnormalities secondary to varicella infection
-Third trimester, spontaneous abortion or premature birth, may occur
-If the mother develops primary varicella close to birth then there is a significant risk of disseminated varicella in the child with significant mortality.
Clinical features of Herpes Zoster (shingles)
-10-20% of individuals during their lifetime suffer zoster, in which there is a dermatomal pattern of vesicles on a red base, which then pustulate, crust and may scar.
-Pain usually precedes the visible lesions, and astute clinicians may make the diagnosis before the rash becomes apparent.
Complications of shingles
-Post herpetic neuralgia may also occur, and may be chronic over many years, even leading to suicide.
-Particular care has to be taken if the first branch of the trigeminal nerve is involved as ocular complications, including keratitis may occur.
-The second branch of the trigeminal nerve may lead to blisters on one half of the palate or tongue.
-Ear involvement may be accompanied by facial nerve paralysis.
Treatment of shingles
-Aciclovir, or related drugs, shorten the course of zoster.
-In immunocompromised individuals, IV agents should be used.
-Post-herpetic neuralgia may be a significant clinical issue, and expert advice from a pain physician or neurologist may be beneficial.
=Classically there is a unilateral band like distribution with a sharp cut off in the mid line.
-Vaccination in later life, reduces the subsequent risk of shingles, and complications by around 50%, and such vaccination programs take place in many countries (including Scotland for those over 70). Some other countries vaccinate against chickenpox earlier in life
