Pruritic Skin Infections Flashcards

1
Q

t/f family history of atopy is important to elicit in atopic dermatitis

A

true, bronchial asthma, acute rhinitis, hay fever, allergies, eczema

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2
Q

an exaggerated whealing tendency when skin is stroked, often seen in patients with atopy

A

dermographism

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3
Q

what is atopic dermatitis

A
  • chronic, pruritic inflammatory skin disease
  • frequently in children (3-6 mos, by 5 years)
  • resolves by adulthood
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4
Q

pathogenesis of ad: outside-inside theory

A
  • primary trigger: epidermal barrier defect from flaggrin gene mutations
  • signal cascades -> cutaneous inflammation
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5
Q

pathogenesis of ad: inside-outside theory

A
  • genetic factors predispose patient with ad to develop abnormally high number of type 2 helper t cells
  • produce proinflammatory cytokines
  • increase vascular permeability, vasodilation, and inflammation
  • compromise in skin barrier and antimicrobial defense
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6
Q

hanigin and rajka criteria: major features

A

3 or more of:

  • pruritus
  • facial and extensor involvement
  • chronic/relapsing dermatitis
  • personal/fhx of atopic diseases
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7
Q

hanigin and rajka criteria: minor features

A

read!!

  • xerosis
  • pityriasis alba
  • keratosis pilaris
  • allergic shiners
  • palmar hyperlinearity
  • ichthyosis vulgaris
  • dermographism
  • nipple eczema
  • cheilitis
  • foot dermatitis
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8
Q

treatment for ad

A

topical corticosteroids (mometasone cream), phototherapy, immunosuppression, basic skin care, trigger avoidance

read guideline

antihistamine: short term, sedating (1st gen)

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9
Q

ddx for ad

A

contact dermatitis

urticaria

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10
Q

allergic contact dermatitis vs irritant contact dermatitis

A

acd: type IV hypersensitivity, repeated exposure
icd: mechanical or chemical injury to skin without specific immunity, single exposure

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11
Q

skin findings in contact dermatitis

A

acute: inflammatory papules and vesicles coalescing into plaques
subacute: erythematous patches with scaling or desquamation
chronic: lichenified plaques with pigmentation and excoriations

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12
Q

distribution and arrangement of contact dermatitis

A

distribution: exposed areas in contact with irritant or allergen
arrangement: well-demarcated patterns suggestive of external cause

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13
Q

diagnosis of contact dermatitis

A

patch test

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14
Q

treatment for contact dermatitis

A
  • identification and removal of offending agent

- betamethasone cream

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15
Q

what is urticaria

A
  • transient and migratory allergic response
  • edematous plaques (wheals)
  • deep dermal swelling (angioedema)
  • severe: respiratory symptoms, vascular collapse and shock
  • any age
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16
Q

pathogenesis of urticaria

A
  • mast cell releases histamine and proinflammatory mediators
  • vasodilation and plasma leakage

acute: <6 wks
chronic: >6 wks

17
Q

most common cause of chronic urticaria

A

spontaneous or idiopathic

18
Q

treatment for urticaria

A
  • first line: second gen antihistamines
  • second line: increase antihistamine, add omalizumab
  • epi for anaphylaxis and airway compromise
  • oral corticosteroids as rescue drug
19
Q

risk factors for scabies

A
  • exposure to close contact!!
  • cramped living conditions
  • atopic dermatitis
20
Q

what is scabies

A
  • infestation of sarcoptes scabiei var. hominis
  • common in children, young adults, and bedridden elderly
  • transmitted by close proximity
21
Q

skin findings in scabies

A
  • pethognomonic: burrows (s/j shape)
  • vesicles, papules, nodules with excoriations, scale, crust
  • loc: interdigits, wrist, elbows, umbilical area, genitals
  • intractable nocturnal pruritus
22
Q

type of scabies in immunocompromised

A
  • crusted or norwegian

immunocompetent: papules, nodules, vesicles

23
Q

diagnosis of scabies

A
  • clinical
  • micrscopic identification of mites, eggs, or fecal pellets
  • dermoscope: delta wing jet sign
24
Q

treatment for scabies

A
  • doc: permethrin 5% lotion
  • lindane 1% (not for young)
  • crotamiton 10% cream
  • precipitated sulfur 5%
  • benzyl benzoate 10%
  • oral ivermectin for immunocompromised
25
Q

ddx for scabies

A

pediculosis

arthropod bites

26
Q

types of pediculosis

A

pediculus humanus capitis: head louse
pediculus humanus humanus: body or clothing louse
phthirus pubis: pubic or crab louse

27
Q

what is pediculosis capitis

A
  • most common in children 3-12 yo
  • presence of eggs/nits firmly attached to scalp hair!!!
  • transmitted from person to person (close contact, shared objects)
28
Q

diagnosis of pediculosis capitis

A
  • demonstrating egg capsules on hair shafts

- bites = erythematous macules or papules with excoriations

29
Q

infections transmitted by body lice

A

epidemic typhus, trench fever, relapsing fever

30
Q

risk factors for pediculosis corporis

A

inability to wash and change clothing, crowded living conditions, poor hygiene

31
Q

what is pediculosis pubis

A
  • crab lice or pubic lice
  • hair bearing sites
  • transmission: sexual contact, close contact, fomites
32
Q

management of pediculosis

A

pediculicides

  • pyrethrin
  • permethrin
  • lindane
  • benzyl alcohol
  • malathion!!
  • topical and oral ivermectin!!
33
Q

what are arthropod bites

A
  • intensely pruritic eruption occurring hours to days after exposure to insect
  • children > adults
  • spring and summer
34
Q

etiology and pathophysio of arthropod bites

A

etiology: mosquitoes, gnats, fleas, mites, bedbugs
pathophysio: type 1 hypersensitivity reaction from injected foreign

35
Q

skin findings in arthropod bites

A
  • erythematous macules, papules, vesicles, excoriations
  • round or domed
  • groups of three
  • legs > arms > trunk
36
Q

diagnosis of arthropod bites

A
  • clinical picture

- histopath

37
Q

treatment of arthropod bites

A
  • topical corticosteroids
  • antihistamines
  • insect repellants (deet or citronella)
  • flea/tick control