Pruritic Skin Infections Flashcards
t/f family history of atopy is important to elicit in atopic dermatitis
true, bronchial asthma, acute rhinitis, hay fever, allergies, eczema
an exaggerated whealing tendency when skin is stroked, often seen in patients with atopy
dermographism
what is atopic dermatitis
- chronic, pruritic inflammatory skin disease
- frequently in children (3-6 mos, by 5 years)
- resolves by adulthood
pathogenesis of ad: outside-inside theory
- primary trigger: epidermal barrier defect from flaggrin gene mutations
- signal cascades -> cutaneous inflammation
pathogenesis of ad: inside-outside theory
- 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
hanigin and rajka criteria: major features
3 or more of:
- pruritus
- facial and extensor involvement
- chronic/relapsing dermatitis
- personal/fhx of atopic diseases
hanigin and rajka criteria: minor features
read!!
- xerosis
- pityriasis alba
- keratosis pilaris
- allergic shiners
- palmar hyperlinearity
- ichthyosis vulgaris
- dermographism
- nipple eczema
- cheilitis
- foot dermatitis
treatment for ad
topical corticosteroids (mometasone cream), phototherapy, immunosuppression, basic skin care, trigger avoidance
read guideline
antihistamine: short term, sedating (1st gen)
ddx for ad
contact dermatitis
urticaria
allergic contact dermatitis vs irritant contact dermatitis
acd: type IV hypersensitivity, repeated exposure
icd: mechanical or chemical injury to skin without specific immunity, single exposure
skin findings in contact dermatitis
acute: inflammatory papules and vesicles coalescing into plaques
subacute: erythematous patches with scaling or desquamation
chronic: lichenified plaques with pigmentation and excoriations
distribution and arrangement of contact dermatitis
distribution: exposed areas in contact with irritant or allergen
arrangement: well-demarcated patterns suggestive of external cause
diagnosis of contact dermatitis
patch test
treatment for contact dermatitis
- identification and removal of offending agent
- betamethasone cream
what is urticaria
- transient and migratory allergic response
- edematous plaques (wheals)
- deep dermal swelling (angioedema)
- severe: respiratory symptoms, vascular collapse and shock
- any age
pathogenesis of urticaria
- mast cell releases histamine and proinflammatory mediators
- vasodilation and plasma leakage
acute: <6 wks
chronic: >6 wks
most common cause of chronic urticaria
spontaneous or idiopathic
treatment for urticaria
- first line: second gen antihistamines
- second line: increase antihistamine, add omalizumab
- epi for anaphylaxis and airway compromise
- oral corticosteroids as rescue drug
risk factors for scabies
- exposure to close contact!!
- cramped living conditions
- atopic dermatitis
what is scabies
- infestation of sarcoptes scabiei var. hominis
- common in children, young adults, and bedridden elderly
- transmitted by close proximity
skin findings in scabies
- pethognomonic: burrows (s/j shape)
- vesicles, papules, nodules with excoriations, scale, crust
- loc: interdigits, wrist, elbows, umbilical area, genitals
- intractable nocturnal pruritus
type of scabies in immunocompromised
- crusted or norwegian
immunocompetent: papules, nodules, vesicles
diagnosis of scabies
- clinical
- micrscopic identification of mites, eggs, or fecal pellets
- dermoscope: delta wing jet sign
treatment for scabies
- doc: permethrin 5% lotion
- lindane 1% (not for young)
- crotamiton 10% cream
- precipitated sulfur 5%
- benzyl benzoate 10%
- oral ivermectin for immunocompromised
ddx for scabies
pediculosis
arthropod bites
types of pediculosis
pediculus humanus capitis: head louse
pediculus humanus humanus: body or clothing louse
phthirus pubis: pubic or crab louse
what is pediculosis capitis
- 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)
diagnosis of pediculosis capitis
- demonstrating egg capsules on hair shafts
- bites = erythematous macules or papules with excoriations
infections transmitted by body lice
epidemic typhus, trench fever, relapsing fever
risk factors for pediculosis corporis
inability to wash and change clothing, crowded living conditions, poor hygiene
what is pediculosis pubis
- crab lice or pubic lice
- hair bearing sites
- transmission: sexual contact, close contact, fomites
management of pediculosis
pediculicides
- pyrethrin
- permethrin
- lindane
- benzyl alcohol
- malathion!!
- topical and oral ivermectin!!
what are arthropod bites
- intensely pruritic eruption occurring hours to days after exposure to insect
- children > adults
- spring and summer
etiology and pathophysio of arthropod bites
etiology: mosquitoes, gnats, fleas, mites, bedbugs
pathophysio: type 1 hypersensitivity reaction from injected foreign
skin findings in arthropod bites
- erythematous macules, papules, vesicles, excoriations
- round or domed
- groups of three
- legs > arms > trunk
diagnosis of arthropod bites
- clinical picture
- histopath
treatment of arthropod bites
- topical corticosteroids
- antihistamines
- insect repellants (deet or citronella)
- flea/tick control
