Cutaneous Infections Flashcards
Who gets Impetigo? Describe its level of Infectiousness. What causes it? what is seen? where does it normally occur?
- common superficial bacterial infection usually caused by Staphylococcus aureus and sometimes streptococcus pyogenes.
- small vesicles that rupture and are replaced by thick yellow crust (honey-colored)
- mouth, nose and extremeties are most commonly affected
- common in childhood
What is Bullous impetigo?
caused by the epidermolytic toxin of staph aureus, not the bug itself. so a culture wont show a lot of bug. it is a bullous form of impetigo, less common
WHat is staphylococcal scalded skin syndrome? WHo gets it and what causes it and what is the target of destruction?
- primarily affects infants and children
- toxin-mediated type of exfoliative dermatitis
- toxigenic strains of staph aureus (phage group II, tpe 71)
- 2 exotoxins epidermolytic toxin a (ET-A) and epidermolytic toxin B (ET-B) cause intraepidermal splitting through the granular layer by targeting desmoglein 1.
WHat 2 toxins cause staph scalded skin syndrome
ET-a and ET-B
How does scalded skin syndrome present?
- sudden onset of skin tenderness and a macular eruption, followed by development of large flaccid bulae
- face, neck and trunk including axillae and groin
- mucous membranes are not involed
- good prognosis in children
- in adults staphylococcal septicemia may ensue
Describe the histopathology of staph scalded skin syndrome
subcorneal splitting of the epidermis. a few acantholytic cells and sparse neutrophils amy be present within the blister
**splitting at the granular layer
WHat is cellulitis? what is it also called? where is it most common? What causes it?
- diffuse inflammation of connective tissue of skin and/or deeper soft tissues
- most common on legs
- expanding area of erythema (tender)
- caused by B-hemolytic streptococci (GAS) and or/ coagulase postive staphylococci. although could be other organisms
WHat is Erysipelas? Who gets it and how is it treated
- distinctive type of cellulitis which has an elevated border and spreads rapidly
- more common in males, and over age 65
- occurs on lower extremities and not face
- oral antibiotics for mild disease, and IV antibiotics for severe
WHat is the histopathology of Cellulitis and Erysipelas?
marked dermal edema and lymphatic dilation
diffuse infiltrate of enutrophils that is accentuated areound blood vessles
What virus is commonly associated with warts? what 3 kind of warts are associated?
Human Papilloma virus (DNA)
- Verruca vulgaris, plantar warts, anogenital warts
- usually self-limited and regress spontaneously within 6 months to 2-3 years
- low risk and high risk HPV causes them. but most are low risk
WHat is the pathology of verrucae (warts)
- verrucous epidermal hyerplasia
- Koilocytosis (cytoplasmic vacuolization) of the upper layer of the epidermis
- infected cells show keratohyaline granules and intracytoplasmic aggregates
What are verruca vulgaris?
most common type of wart occuring anywhere, but most frequently on the hands
What is Verruca plana?
flat wart, common on face or dorsal surface of hands
What are verruca plantaris and verruca palmaris?
soles and palms
Besdies waiting for regression how can ou treat warts?
destructive (cytotherapy), topical (salicylic acid-impregnated bandages) or immunomodulatory (imiquimod cream) which activates immune cells through TLR 7 resulting in an immune response against the warts
Describe the histopathlogy of warts
papillomatous hyperplasia of the epidermis
prominent granular cell layer in which there are enlarged clumps of irregulat basophillic keratohyaline granules. large cells with prominent vacuolated cytoplasm and a small pyknotic nucleus are seen in the upper layers of the epidermis (koilocytes)
What is condyloma accuminatum and what causes it?
- single or multiple papular lesion that are pearly, filiform fungating cauliflower or plaque like
- high risk HPV types (16, 18, 31, 33) increase cancer risk
- low risk (6, 11) are over 90% of all cases and dont increase cancer risk
- STF
Describe the histopathology of condyloma accuminatum
condyloma accuminata are characterized by marked acanthosis ith a broad rounded exophytic growth. the surface is hyperkeratoic and parakeratoic. superfician vacuolated keratinocytes (koilocytes) are characteristic and coarse keratohyaline granules may be rpesent
WHat are the 2 tyoes of herpes simplex virus and what is the difference between the two? WHat does a herpes lesion look like?
HSV1: common in childhood, lips (cold sore, gingivostomatitis)
HSV2: after puberty, genitalia, sexually transmitted
lesions are groups of clear vesicles which heal without scarrring
How does varicella (chickenpox) spread? who gets it? how does the disease progress? and what are some complications?
- highly contagious and spreads through respiratory route (incubtion time 2 weeks)
- disease of childhood
- rash progresses from macules to vesicles to pustules (all stages are simultaneously present)
- complications: reye syndrome, pneumonia, self-limited cerebelitis
How do you get Herpes zoster? who has an increased incidence? describe the rash
- recurrence of VZV years later by reactiation of latent VZV infection-shingles
- increased incidence in the elderly and immunocompromised ts.
- rash has unilateral and dermatomal distribution (thoraz and lumbar)
Describe the pathology of herpes virus
- HSV and VZV show the same histologic changes
- acantholysis of epidermis
- multinucleated keratinocytes with intranuclear inclusions ( cowdry type A inclusions)
- perineural and intraneural inflammation
WHat is a Tzanck smear and when is it done
- a rapid cytological diagnosis
- make a smear from the base of a freshly opened vesicle and stain it with Giemsa stain
- not as sensitive
- test for herpes
What is Mulluscum contagiosum? how do you get it? where do you get it?
- cutaneous infection caused by large brick shaped DNA poxvirus
- children acquire infection from close contact (eyelids, face, axilla) widespread disease can be seen in immunosuppressed patients (HIV)
- highly contagious, self-inoculation
- penis, vulva, groin (STD)
- **shiny, dome-shaped papule, not quite a vesicle. often skin colored, can be red and inflammaed***
Describe the pathology of molluscum contagiosum
- inverted nodule “crater like”
- eosinophillic cytoplasmic bodies (Molluscum bodies “Henderson-Patterson bodies)
- **bright-stained, symetric looking papules
WHat kind of reaction is scabies? What causes scabies> what is scabies?
- arthropod reaction
- contagious caused by mite Sarcoptes scabiei
- transmitted via prolonged direct human contact and rarely by fomites
- extremely pruritic papulovesicular eruption (sometimes burrows)
- fingers, penis, umbilicus, waistband, axilla hands
- erupts 4 weeks after infestation
Describe the histopathology of scabies
fertilize female S. scabei mite deposits eggs in the burrows in the epidermis. the burrows extend at a shallow angle through the stratum corneum and may reach the deeper epidermis. eggs, jarvae, mite parts, and excreta may be identified in the stratum corneum
what does Tinea versicolor present as clinically? how do you treat it?
multiple irregular areas of hypo or hyperpigmentation, which are circular and macular and may becom confluent
topical or oral antifungals can be used
What is the histopathology of tinea versicolor?
stratum corneum contains round budding yeast and short septated hyphae, imparting the spaghetti and meatballs appearance. organisms are clearly seen in H&E ad PAS presentations
