describe the appearance of skin in acute dermatitis
describe the appearance of chronic dermatitis
red, scaly, lichenified with fissures, thickened
what is a common symptom of all types of dermatits
for allergic contact dermatits (ACD), what is the pathogenesis
delayed type (type IV) T cell mediated hypersensitivity rxn
for the delayed type HSR seen in ACD, what are the 2 phases?
sensitization (induction) - req 10-14 days and elicitation (challenge) - re-exposure, dermatitis appears w/in 12-48 hours
what is the most common cause of ACD? what environmental allergens cause this? what is the chemical?
poison ivy, oak, sumac
urushiol - a resin
what is the 2nd most common cause of ACD?
nickel (think jewlery) that ain't a igloo, that's my watch and that ain't snow baby thats my chain, that's not ice girl, that's my teeth and that's not a snowcone, that's my ring
ACD the main symptom is pruritis, what is the common presentation? appearance of their skin
eczematous, scaly edematous plaques w/ vesiculation distributed in areas of exposure
what is a key finding in the presentation of Rhus allergy
linear streaks unique distribution tells you it is contact from the external
what is the appearance of the lesions seen in Rhus allergy?
what do they start off as and what do they become? what forms after 1-2 days?
lesions begin as erythematous macules that become papules or plaques
blisters form over 1-2 days
treatment of SEVERE Rhus dermatitis? what about duration of this therapy and why?
oral steroids, especially if topical steroids are failing must give for 2-3 weeks - if given for less, pts may relapse
treatment of normal Rhus dermatitis
minor supportive care - topical steroids, oral or topical antihistamines - to improve pruritis, soothing shit like oatmeal baths and calamine lotion
what are the characteristics of eyelid allergic contact dermatitis
scaling red plaques on upper eyelids (lower less common) intensely pruritic caused by transfer from hands
common causes of eyelid allergic contact dermatitis
for evaluation of dermatitis, what is a test to identify specific allergens?
since not all pts w/ ACD need patch testing, when should you refer a pt for patch testing
when the allergen is unclear or the dermatitis is chronic
does a positive reaction of patch testing determine the cause of the pts rash? what confirms the clinical relevance of the positive patch test?
no - positive reaction does not mean the rash is due to that specific allergen
elimination of the rash with removal of the allergen confirms the clinical relevance of the positive patch test
this obviously dumb, but what is the number 1 treatment of ACD?
avoid exposure to the offending substance (big,bold, could be test question)
what are the 1st and 2nd most common locations that we talked about for nickel dermatitis?
bridge of nose and around the ears - from glasses
around the umbilicus - from belt buckles erythematous plaque with papules
what ACD can present with a delayed or immediate type HSR?
where does the dermatitis usually present for the delayed type of latex allergy
dorsum of hands
what are some other findings associated with the immediate HSR latex allergy?
disseminated urticaria, allergic rhinitis, and/or anaphylaxis
what are the two types of contact dermatitis?
allergic and irritant
define irritant contact dermatitis
ICD - inflammatory rxn in skin resulting from exposure to a substance that can cause an eruption in most people who come in contact with it NON-IMMUNOLOGIC
is previous exposure necessary in ICD
what is the general mechanism of causation in ICD
repeated application from mildly irritating substances (may occur from a single application w/ severely toxic substances, but this is not MC)
what type of disease is ICD? what 2 elements play a role?
multifactorial disease both exogenous (irritant and environmental) and endogenous (host) elements play a role
what is the most important exogneous factor for ICD
the inherent toxicity of the chemical for human skin
what are the most common sites on the body for ICD involvement and why (endogenous elements)
there are site differences in barrier function - skin is thinner
face, neck, scrotum, and dorsal hands more susceptible
what is a major risk factor for irritant hand dermatitis
impaired barrier function
and lower threshold for skin irritation
what are the more common findings in mild ICD
erythema, chapped skin, dryness, and fissuring w/ repeated exposures over time
ICD - what do severe cases present with - clinical findings of skin
edema, exudate, tenderness
what do potent irritants cause in ICD
what is the mainstay of treatment for ICD
identification and avoidance of the potential irritant
when should you perform patch testing with ICD and why
in cases with suspected chronic irritant dermatits (occupational cases) to exclude an allergic contact dermatitis
what is one of the most common skin disorders in developed countries?
atopic dermatitis (AD) 20% of children and 1-3% of adults
what is the definition of atopic dermatitis
AD is a chronic, pruritic, inflammatory skin disease w/ a wide range of severity
what is the primary symptom of AD and what is AD often called
pruritus "the itch that rashes" scratching to relieve AD-associated itch gives rise to the "itch-scratch" cycle and can exacerbate the dz
what is the importance of age in AD?
distribution and morphology of skin lesions varies by age
for AD, what kind of lesions do infants and toddlers develop?
eczematous plaques appear on the cheeks, forehead, scalp and EXTENSOR surfaces
for AD, what type of lesions develop in older children and adolescents?
lichenified, eczematous plaques on FLEXURAL areas of neck, elbows, wrists, ankles
for AD, what type of lesions develop in adults?
Lichenification in flexural regions and involvement of hands, wrists, ankles, feet and face - forehead and around eyes
what is a common characteristic at all stages of AD
Xerosis - dry skin
what type of HSR is atopic dermatits
AD - inflammatory Type I HSR
what is the triad of AD, the "atopic triad"?
AD, allergic rhinitis, bronchial asthma
what is the name of the periorbital findings in AD?
Dennie Morgan folds around the eyes (pleats underneath the eyes)
what is the pathogenesis of AD? what are 4 factors that play a role
Genetics, skin barrier dysfunction, impaired immune response, environment
what is a major pre-disposing factor for AD (genetic)
Inherited reduction or loss of the epidermal barrier protein filaggrin
what type of immunity does AD favor?
Th2 mediated immunity
what does treatment of AD include (long term use mainly)
long-term use of emollients and gentle skin care - also short term treatment for acute flares
AD - how do you treat the acute inflammation associated with it? (this was one of his key points)
another key point of treatment of AD, what do you do incases of secondary bacterial skin infections
what is an example of emollients used in treatment of AD
what is the methodology / reason for using emollients in AD?
they help to compensate/restore the genetically determined impaired epidermal barrier function (he mentioned this twice)
what are 3 types of treatment used for more severe cases of AD?
immunomodulators - topical tacrolimus or pimecrolimus
phototherapy - in refractory cases
what is the most common cause (MCC) of infected atopic dermatitis?
what findings indicate infection in atopic dermatitis
presence of erosions, drainage with yellow crusting
what is Eczema Herpeticum
severe HSV infection in an atopic patient (overlies existing AD)
how does Eczema Herpeticum present
multiple wide spread monomorphic "punched-out" discrete erosions w/ hemorrhagic crusting
what is the treatment of Eczema herpeticum
systemic antivirals - acyclovir
severe cases may require hospitalization
what is the presentation of Nummular Dermatitis?
round, coin shaped, light pink, scaly, thin, 1-3 cm plaques
when does nummular dermatitis/ discoid eczema worsen?
during the winter, due to less humidity in the air, increasing skin dryness
where on the body does nummular dermatitis/ discoid eczema develop?
legs, dorsal hands, extensor surfaces, and the trunk
what is the pathogenesis of nummular dermatitis
unknown - may be linked to impaired skin barrier function
what pt population is nummular dermatitis more common in
treatment of nummular dermatitis
same as AD or other eczema -corticosteroids, tacrolimus, and emollients however, a number of patients will require phototherapy to clear lesions
what is the pathogenesis of Dyshidrotic Dermatitis (Pompholyx)
course is unknown and NOT related to dysfunction of sweat glands
what is the presentation of Dyshidrotic Dermatitis (Pompholyx)
group of 2-5 mm vesicles, somtimes likened to tapioca pudding
where does Dyshidrotic Dermatitis (Pompholyx) commonly occur?
lateral fingers, central palsm, insteps, lateral borders of feet
what are the symptoms of Dyshidrotic Eczema/ Pompholyx
very pruritic, burning - prickling sensations
what are the associations of Dyshidrotic Eczema/ Pompholyx
Atopic dermatitis and contact dermatitis (allergic and irritant)
define Lichen Simplex Chronicus
Chronic, intensely pruritic skin condition triggered by repeated rubbing and scratching of the skin
what is the presentation of Lichen Simplex Chronicus
solitary, well-defined, pink to tan, thick, and lichenified plaque
what are the common locations of involvement of Lichen Simplex Chronicus
lateral neck, scrotum/vulva, and dorsal foot
areas easily accessible by scratching