Dermatology: allergic and immune-mediated disorders Flashcards
define atopic dermatitis
aka eczema
a relasping inflammatory skin disorder that is common in infancy
characterized by pruritus leading to lichenification
pt with atopic dermatitis are at increased risk of what?
increased risk of 2nd bacterial (S aureus) and viral (HSV or molluscum) infection
name common triggers of eczema?
climate, food, contract will allergens, or physical or chemical irritants, and emotional factors
how does eczema present in infants? what area is usually spared?
- erythematous, edematous, weeping, pruritic papules and plaques on the face, scalp, and extensor surfaces of extremities
- diaper area is usually spares
how does eczema present in children
dry, scaly, pruritic, excoriated papules and plaques in the flexural areas and neck
how does eczema present in adults? what 2 areas are often involved?
lichenfication and dry fissures skin in flexural distribution. often hand or eyelid involvement
how is eczema diagnosed?
diagnosis is clinical
pt may have mild eosinophilia and increased IgE
what is atopic dermatitis commonly associated with? 2
asthma and allergic rhinitis
how is eczema prophylactically treated?
nondrying soaps, applications of moisturizers, and avoidance of known triggers
name 1st line treatment for eczema? what is used in pt >2yrs of age with moderate to severe?
tropical corticosteroids topical immunodulators (tacrolimus, pimecrolimus) are useful moderate to severe if pt is >2 yrs of age
how long should corticosteroids be used in treatment of eczema?
topical corticosteroids should not be used for longer than 2-3 wks to avoid decreasing the integrity of the skin
how is erythema toxicum neonatorum defined? how is it treated?
-begins 1-3 days after delievery and resembles eczema, presenting with red papules, pustules, and or vesicles with surrounding erythematous halos.. increases eosinophils are present in pustules or vesicles. usually resolves in 1-2 wks with no treatment
how is contact dermatitis defined?
a type IV hypersensitivity reaction that results from contact with an allergen to which the pt has previously been exposed and sensitized. more common in adults in children
how does contact dermatitis present?
pruritus and rash
can also present with edema, fever, and lymphadenopathy
name some common allergens in contact dermatitis?
poison ivy, poison oak, nickel, soaps, detergents, cosmetics,and rubber products containing latex (gloves and elastic bands in clothing)
what is shape of rash in contact dermatitis?
often mimics that of exposing object and characteristic distributions of involvement are often seen where makeup, clothing perfume, nickel jewelry, and plants
-it can spread over body via transfer of allergen by the hands or via circulating T lymphocytes
how can contact dermatitis be diagnosed?
- clinical impression
- patch testing can be used to establish the causative allergen after the acute phase rash has been treated
how is contact dermatitis treated?
prophylaxis consist of avoiding allergen
topical or systemic corticosteroids as needed with cool, wet compresses to soothe crusted lesions of skin
an infant with a history of ecczema treated with corticosteroids is brought in for a new-onset rash and fever. physical examination reveals grouped vesicles involving eczematous areas of the infant’s extremities and face. what is appropriate therapy?
this infant has eczema herpeticum a medical emergency that is due to propensity for HSV infection to spread systemically, potentially affecting the brain. acyclovir must be started immediately!
how is seborrheic dermatitis defined?
a common disease that may be caused by Malassezia furfur a generally yeast found in sebum and hair follicles. it has predilection for areas with oily skin
name appearance of seborrheic dermatitis in infants
presents with severe, red diaper rash with yellow scale, erosions, and blisters. a thick crust “craddle cap” may be seen on the scalp
name appearance of seborrheic dermatitis in children/adults
red, scaly patches are seen around the ears, eye brows, nasolabial fold, midchest, and scalp. the rash is more localized and less dramatic than that seen in infants
name groups of pts are risk for severe seborrheic dermatitis?
HIV/AIDS
Parkinson’s disease
how is seborrheic dermatitis diagnosed? what two illnesses should be ruled out
clinical impression
rule out contact dermatitis and psoriasis
name treatment for seborrheic dermatitis?
selenium sulfide or zinc pyrithione shampoos for scalp,
topical antifungals or corticosteroids for other areas
how is craddle cap treated?
often resolves wit routine bathing and application of emollients in infants
how is psoriasis defined
A t-cell mediated inflammatory dermatosis characterized by erythematous plaques with silvery scales due to dermal inflammation and epidermal hyperplasia
when does psoriasis start?
starts in puberty or young adulthood
where are psoriasis lesions found?
classically on extensor surfaces, including elbows, knees, scalp, and lumbosacral regions
what happens to pts nails in psoriasis?
pitting- oil spots
onycholysis (lifting of nail plate)
what is it called when psoriatic lesions are caused by irritation or trauma?
Koebner’s pnenomenon
what medications can cause psoriasis?
beta-blockers, lithium, and ACEIs
what is Auspitz sign? and what disease is it associated with?
bleeding when scale is scraped.
psoriasis
what histological findings are in psoriasis?
thickened epidermis, elongated rete ridges, absent granular cell layer, preservation of nuclei in stratum corneum (parakertosis), and sterile neutrophilic infiltrate in stratum corneum (Munro’s microabscess)
how is psoriasis treated? what is used for severe cases
topical steroids
keratolytic agents, tar, antralin along with UV therapy
metrotrexate for severe cases
retinoids and vitamin D3 analogs can also be used
a 23 yr old female is seen for an itchy, linear rash on her right leg. She return from a camping trip 4 days a ago and denies using any new makeup clothing or jewelry. what features of this presentation factor a contact dermatitis?
the asymmetric involvement of the rash, its linear arrangement (possibly from contact with a plant during a camping trip) and the time from exposure to rash presentation all point to contact dermatitis
rash common affecting extensor surfaces think?
flexor surfaces think?
psoriais
atopic dermatitis
5% of pts with psoriasis also have what contidition
seronegative arthritis
how is urticaria defined. what is it’s timeline?
- characterized by superficial, intense erythema and edema in a localized area.
- usually acute but can also be chronic
name etiology of urticaria
results from histamine and prostaglandins from mast cells in a type I HSN RXN
describe typical lesion in urticaria
elevated papule or plaque that is reddish or white and variable in size. widespread and last a few hrs
what can happen in severe cases of urticaria
extracutaneous manifestations
such as tongue swelling, angioedema (deeper more diffuse swelling), asthma, GI symptoms, joint swelling, and fever
name common triggers of urticaria
food, drug, virus, insect but, or physical stimulus.
how is urticaria diagnosed?
clinical impression
name treatment of urticaria
systemic antihistamines,
anaphylaxis=epinephrine IM, antihistamines, IV fluids, and airway maintenance
define drug eruption
rxn takes many forms
can call all 4 types of HSN RXN
one drug can cause different rxns in different pts
what do drug eruption occur?
- usually 7-14 days after exposure
- if pt reacts within 1-2 days of starting a new drug, that drug is probably not causative agent
describe lesion of drug eruption
generally widespread, relatively symmetrical, and pruritic
how long does drug eruption last?
most are short-lived, disappearing within 1-2 wks following removal of offending agent
name some extreme complications of drug eruptions
erythhroderma, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN)
how is drug eruption treated?
discontinue offending agent, treat symptoms with antihistamines and topical steroids to relieve pruritius
what is common on histology in pts with drug eruptions
pts often have eosinophilia and eosinophilia on histopathology
how is erythema multiforme defined
cutaneous rxn with targetoid lesions that has many triggers and is other recurrent
where can erythema muliforme occur? and how do lesions start?
- can occur on mucus membranes, palms and sole are often affected.
- start as erythematous macules that become centrally clear and then develop a blister
what are signs and symptoms of erythema multiforme?
fever, myalgias, HA, and arthralgias
what complications can occur as a result from erythema multiforme
in minor form disease is uncomplicated
but EM major can lead to TEN or SJS
name common triggers of erythema multiforme
recurrent HSV infection of the lip. other common triggers are drugs and mycoplasmal infections
how is erythema multiforme treated?
treat symptoms, systemic corticosteroids are of no benefit
minor cases treat with antipruritics
major cases treat as burns
how are Steven Johnson Syndrome and Toxic Epidermal Necrolysis defined?
SJS/TEN are on 2 different point of the spectrum of life-threatening exfoliative mucocutanteous diseases
SJS30% of BSA
what are SJS/TEN caused by?
drug induced
what can SJS and TEN be preceded by what diseases?
erythema multiforme, flulike prodrome, skin tenderness, a maculopapular drug rash, or painful outh lesions
what is SJS and TEN associated with?
history of exposure to new drugs, sulfonamindes, penicillin, seizure medications (phenytoin, carbamazepine), quinolones, cephalosporins, allopurinol, corticosteroids, or NSAIDs
what is expected on PE for SJS and TEN
examination reveals severe mucosal erosions (eyes, mouth, genitals) with widespread erythematous, dusky red or purpuric macules or atypical targetoid lesions
what happens to skin on palpation in SJS and TEN?
Nikolsky’s sign (separation of superficial skin layers with slight rubbing) and epidermal detactment
what are result of biopsy in SJS
shows degeneration of the basal layer of the epidermis
what are the results of biopsy of TEN
full thickness eosinophilic epidermal necrosis
what should be in the differential for SJS and TEN?
staphylococcal scaled-skin syndrome (SSSS), graft vs host rxn (usually after bone arrow transplant), radiation therapy, and burns
SJS and TEN vs Staphylcoccal scaled skin syndrome
age
etiology
SSSS: children <6 and infectious cause
SJS/TEN: adults and drug rxn
name complications for SJS/TEN
pt have the same complications as burn victims, thermoregulatory difficulties, electrolyte disturbances, and infections
name treatment of SJS and TEN?
- skin coverage and maintenance of fluid and electrolyte balance.
- corticosteroids in the early stages becasuse there is high risk mortality
how is erythema nodosum defined
panniculitis or inflammatory process of the subcutaneous adipose tissue
name triggers of erythema nodosum
- infection (Streptococcus, Coccidiodes, Yersinia, TB),
- drug rxns (sulfonamides, various antibiotics, OCPs)
- chronic inflammatory diseases (sarcoidosis, Crohn’s disease,
- ulcerative colitis, Beehcet’s disease)
name signs and symptoms of erythema nodosum
- painful, erythematous nodules appear on pts lower leg, slowly spread turning brown or gray.
- may present with fever and joint pain
what lab tests may be false + in pts with erythema nodosum
VDRL
what is workup for erythema nodosum?
ASO titer, a PPD test in high risk pts, an CXR to rule out sarcoidosis or a small bowel series to rule out IBD based on pts complaints
how is erythema nodosum treated?
remove triggering factor and use NSAIDs
