Viral Infections Associated With Skin Manifestations Flashcards
Some viruses cause changes in the skin indirectly and diffusely by
Examples
Appearance
D.x:
First causing derangements of internal organ function, including of cells of the immune system
Nonspecific viral exanthems- very common in children. No physical features reveal virus identity
Blanchable erythematous macules and papules, often on trunk or extremities (except meningitis is unblanchable)
Seasonal variation, winter often respiratory viruses like influenza adenovirus, RSV
Dx: drug reactions, contact dermatitis, other organisms
Some cause changes in the skin directly and locally, by
Examples
Replicating within the skin and damaging it
Measles, chicken pox, herpes simplex, rubella, roseola, erythema infectiosum
Scabies mites:
Dig tunnels in skin to lay eggs, often between fingers, at waistline, itchy allergic reaction common, easily spread, treat household, thorough laundering/vacuuming, permethrin lotion- neurotoxic to mites
Bedbugs bite:
Exposed skin at night (in contrast, fleas tend to bite ankles), see blood on sheets, exterminator
Lice
The louse attaches to hair, feed on blood, remove with nit comb/insecticidal shampoo
Ticks can:
Spread Lyme disease via bacterium Borrelia burgdorferi or Rocky Mountain spotted fever via bacterium Rickettsia ricekttsii, each associated with rashes
Kissing bugs (triatomine bugs) may spread the parasite:
Trypanosoma cruzi that causes Chaga’s disease (which can cause serious myocarditis)
Exanthem
Widespread symmetric rash (often feverish)- from microbe or drug or autoimmunity.
From a virus is an example of a febrile reaction, where events related to the infection lead to an elevation of hypothalamic set point (mechanisms of exogenous and endogenous pyrogens).
That elevation, in febrile reactions, commonly causes patients to feel cold/chills as their temperature is rising
In contrast, when a patient’s temperature is rising doe to a non-febrile hyperthermia (malignant hyperthermia), the patient commonly feels like they are burning up.
Enanthem
Rash of muscles membranes- like the mouth
Common maculopapular rashes
Pharmacological drug related- common in adults, including hospitalized. Also called a drug eruption, drug exanthem- ampicillin, NSAIDs, others. Can be morbilliform rash
Virus related- common cause in children worldwide- measles, reseola, rubella, various respiratory agents
Insect bites, food allergies- adults and children common
Maculopapular rash often arising in weeks following an HIV infection
HIV seroconversion exanthem
Kaposi sarcoma histology findings
Causative agent
Slit-like spaces filled with blood
Human herpes virus 8
Prevalence of tumor dropped massively with the introduction of highly active anti-retroviral (HAART) drug therapy for HIV infection
May present clinically with red patch that many be raised
Molluscum contagiousum histology
Causative agent
Virus accumulates in the skin in aggregations called molluscum bodies
Molluscum contagiosum virus
Very common cause of skin infection, especially anogenital regions, commonly spread by direct contact, in immune compromised (AIDs), more florid involvement includes face
No vaccine, treatments not very effective (include liquid nitrogen freezing)
Measles- “Red measles, Rubeola” causative agent
Transmission
Signs- early/first two week course
Measles virus (rubeola virus)
Transmitted by direct contact with respiratory secretions (droplets)
One of the most communicable diseases
In two weeks, virus first replicates in respiratory tract, then spreads to lymphatic tissue, then to blood (viremia), then to conjunctiva and skin (rash at 2 weeks)
Early signs- 3 C’s: cough, coryza (runny nose), conjunctivitis
Replication of measle’s virus occurs in both
Epithelial cells and leukocyte resulting in Warthin Finkeldey cells (multi-nucleated that also arise in lymph nodes)
Koplik’s spots
oral cavity lesions said to be pathognomic for measles, arising just after the skin rash, the result of mucosal ulceration of buccaneers mucosa near molars (may seem white-sigh or blue-ish centers on a red base)
May be associated with other mucosal linings
Rash description of measles
Complications
Descending rash- result of immune mediated activity, so in immune compromised patients, the rash may be markedly attenuated- involves T cells targeting virus in small blood vessels. Morbilliform.
Encephalitis, bacterial pneumonia and bacterial otitis media (arise from virus induced immunosuppression in part)
Febrile condition can induce premature labor or miscarriage
Mortality is higher in AIDs patients
Chicken pox causative agent
Varicella (acute infectious disease historically acquired in childhood) - zoster (recurrent, painful infection often occurring decades later) virus
Vesicular eruptions of zoster tends to be
Unilateral, involving the distribution of the sensory nerve (dermatome) in which latency of virus was interrupted
Neonatal rashes and jaundice- TORCHES
Perinatal infections that can be vertically transmitted and associated with congenital anomalies, rash, hepatosplenomegaly, jaundice and other changes
Toxoplasmosis, other (syphillis, varicella-zoster, parvovirus V19), rubella, cytomegalovirus, herpes
Small pox causative agent and types
Various virus- only infects humans
Centrifugal- rash distributes to face and distal parts, including arms and soles involvement different from chicken pox
Variola major (highly virulent, 30% mortality), variola minor (highly virulent, 1% mortality) Rash is similar to chicken pox morphologically
Verrucae causative agents and types
Human papillomavirus- spread by touching (autoinocculation)
Verrucae Vulgaris- most common type of wart, often on dorsal hand surfaces
Verruca plana- flat wart, face and hands
Verruca plantaris, palmaris- soles, palms
Rare compilation from HPV in pregnancy
Transmission via vaginal delivery, babies swallow the virus, called laryngeal papillomatosis that may obstruct the infant’s respiration
Rubella (German measles) causative agent
Resembles
Rubella virus
Resembles measles in spread by respiratory droplets and rash
teratogenic, high risk to pregnancy- dev malformations esp in first trimester
Affects the skin- blueberry muffin rash: prupuric skin rash, do not blanch with pressure)
Herpes simplex occasional site of involvement that is painful
Histo logically can be
Risk to immunocompromised
Tip of finger- herpetic whitlow
Intranuclear inclusions (Cowdry type A) where virus replication occurs
Serious disseminated infection- lung, liver, esophagus
