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Name 6 vesicular and vesicobullous eruptions
  • HSV I, HSV II
  • Varicella
  • Herpes zoster
  • Impetigo
  • Bullous insect bite reaction
  • Primary skin bullous disorder
For HSV I and HSV II, describe lesions
  • Grouped vesicles on erythematous base
What precipitates HSV outbreaks? (5)
  • UV
  • Menses
  • Fever
  • URTI
  • Immunodeficiency 
Can you tell subtype from lesions?
No, not from lesions, however:
  • Lips: 80-90% HSV1
  • Genitals: 70-90% HSV2 
  • Where does HSV preside?
  • Has most of adult population been exposed? 
  • HSV presides in sensory ganglia
  • Yes, most of adult population has been exposed to HSV
What is varicella commonly known as?
Chickenpox
Describe the lesions in varicella?
Initial lesions are papules that become vesicles
  • Vesicles then crust over
  • Heal with scarring
What is the distribution of lesions in varicella?
Christmas tree (due to hematogenous spread)
What is the etiology of varicella?
Varicella-zoster virus (VZV)
For herpes zoster, describe the prodrome and the lesions
Prodrome of neuritic pain for days to weeks
  • Acute vesicles, then crusted papules 
What is herpes zoster known as?
Shingles
What is the distribution of herpes zoster lesions?
Lesions are unilateral and dermatomal
If you biopsy any of the following conditions, you fill find the same histological findings, which are what? (2)
  • Herpes zoster
  • HSV
  • VZV
Tzanck smear will show multinucleated keratinocytes or acantholytic keratinocytes
What are the 2 types of impetigo?
  • Non-bullous
  • Bullous 
What is the infectious agent in non-bullous impetigo? (2)
  • GAS
  • S. aureus 
Describe the lesions in non-bullous impetigo?
Crusted erosions
Describe the lesions in bullous impetigo?
Vesicles, bullae in addition to crusted erosions
  • Clear or yellow fluid
  • Shallow erosions form if bullae break 
Name the causative agent in bullous impetigo? (1)
S. aureus
Why are bullae easily breakable?
Neutrophils gather beneath stratum corneum
Do bedbugs carry disease?
No
Describe lesions from bedbugs
  • Erythematous papules, vesicles, nodules
  • Tracks of lesions
Name 4 types of follicular eruptions
  • Pityrosporum folliculitis
  • Pseudomonas folliculitis
  • Staphylococcal folliculitis
  • Acne
How can you differentiate types of follicular eruptions?
  • Hot tub exposure? Pseudomonas
  • Distribution of folliculitis
  • Acne has comedones, papules, nodules, cysts
  • Staphylococcal & Pseudomonas are more inflammatory than Pityrosporum
  • KOH and cultures helpful
Describe Pityrosporum folliculitis lesions, typical patient and lab results (culture, KOH)?
  • Monomorphous papules without comedones
  • Patient is sweaty
  • Culture Neg, KOH Pos
Describe pseudomonas folliculitis lesions, history, distribution, treatment
  • Inflammatory follicular-based papules and pustules
  • Involves exposed areas
  • Culture (+) for pseudomonas
  • Self-limited, no Tx
  • History of hot tub exposure
  • Adjust hot tub pH and clean it
Describe staph folliculitis
  • Inflammatory pustules
  • Gram stain and culture positive
Name 5 Annular and Scaling eruptions
  • Tinea corporis
  • Tinea versicolor
  • Secondary syphilis
  • Psoriasis
  • Nummular eczema
How do you diagnose scaling eruptions?
  • Scrape scaling edge for KOH, and culture
  • Distribution: Psoriasis symmetrical and extensor surface
  • Tinea versicolor: Non-inflammatory brown and white scaling patches
  • Tinea corporis: Few lesions with central clearing
Describe tinea corporis lesions
  • Annular scaling edge
  • Well-demarcated plaques
  • Central clearing
  • Single/multiple lesions
  • Usually asymmetrical
  • Scrape the scaling edge for KOH and culture
What is the etiology of tinea corporis?
  • Trichophyton
  • Microsporum 
More generally, what kind of condition is tinea corporis?
Dermatophytosis
In tinea corporis, you can do what diagnostic test that is looking for what?
PAS Stain
  • Looks for fungal hyphae 
Describe the lesion in tinea versicolor
  • Well marginated round scaling brown or light macules
What is the etiology of tinea versicolor?
Malassezia furfur
What are risk factors for malassezia furfur?
  • Warm, humid climate
  • Oily skin
  • Hyperhidrosis 
  • Yong adult
What is found on diagnostic testing for tinea versicolor?
  • KOH (+)
  • "Spaghetti and meatballs" spores and hyphae on microscopy
For secondary syphilis, when does it occur?
2-6 mo. after initial infection
What lesions occur in secondary syphilis?
  • What is a type of wart-like lesion that is associated? 
  • Often a history of painless ulcer first
  • Lesions can involve palms/soles
  • First eruption is macular, then can be papulosquamous, pustular or acneiform
  • Condylmata lata are flat-topped papules in moist areas, especially mouth and ano-genital
What is the etiology of secondary syphilis?
Treponema pallidum
How do you test for secondary syphilis? (2)
  • Serological testing
  • Skin biopsy 
What are 3 types of papular eruptions?
  • Verruca
  • Mollscum contagiosum
  • Insect bites
How can you differentiate papular eruptions? (4)
  • Molluscum: Central punctum and pearly appearance (often with surrounding eczema)
  • Verruca: Dull surface with capillary loops
  • Verruca plana: Minimally elevated flat papules
  • Insect bites: Pruritic and grouped, can also be vesicular
For verruca vulgaris, describe the lesions
  • Firm hyperkeratotic plaques with clefted surface and vegetations
  • Red or brown dots caused by capillary loops 
What is the etiology of verruca vulgaris
HPV
How is verruca vulgaris transmitted and what are the risk factors
  • Transmitted by skin to skin contact, breaks in stratum corneum faciltate epidermal infection
  • Risk factors: immunocompromised, meat handlers
Describe the lesions in molluscum contagiosum
  • Skin coloured umbilicated papules
  • Gentle pressure causing extrusion from central keratotic plug
  • Mollusca undergoing spontaneous regression may have an erythematous halo
Describe etiology and epidemiology of molluscum contagiosum
  • Caused by pox virus
  • Spread skin-to-skin
  • Seen in HIV
  • Common in children, sexually active adults
Name eczematous and pruritic eruptions (4)
  • Eczema
  • Scabies
  • Louse infestation
  • Insect bites
Describe how to differentiate between eczematous/pruritic eruptions
  • Scabies has burrows/nodules
  • Louse infestations will often have no primary lesion
  • Insect bites are grouped
  • Atopic dermatitis (eczema) will have past history with dry skin, hyper-linear planus, flexural distribution
Describe the lesion and distribution in scabies


  • What 2 types of lesions are seen?

Widespread pruritic eczematous eruption


  • Burrows: Serpiginous track with spot at end, scrape burrow for Dx.

  • Nodules: Red/brown nodules in axillary area and groin; can persist after infxn is clear

  • Spares head/neck except infants/elderly

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