2/17 Dermatitis (Atopic, Contact, and Infestations) Flashcards
What is the difference between Dermatosis and Dermatitis and Eczematous dermatitis?
Dermatosis – any pathologic condition involving the skin
Dermatitis – any inflammatory skin disorder
Eczematous Dermatitis – immunologic response (mainly type IV HSR) that involves B/T lymphocytes that result in the release of vasoactive factors that have inflammatory, destructive, or proliferative effects on the skin. 3 phases (acute, subacute, chronic)
What stage of Eczematous Dermatitis is this?
What are some clinical features of this stage?
ACUTE
Erythema
Edema
Vesicles/bulla (serum in the epidermis) - hallmark feature
Oozing (serum reaching the epidermal surface)
What stage of Eczematous Dermatitis is this?
What are some clinical features of this stage?
Sub-acute
Crust
Scales
What stage of Eczematous Dermatitis is this?
What are some clinical features of this stage?
Chronic
Lichenification
Hyper/hypo-pigmentation
What stage of Eczematous Dermatitis is this?
What are some clinical features of this stage?
Chronic
Lichenification
Hyper/hypopigmentation
What stage of Eczematous Dermatitis is this?
What are some histological features of this stage?
ACUTE
Vesicles in the epidermis + EDEMA + keratinocytes cells floating around
spongiosis = pathological hallmark
What stage of Eczematous Dermatitis is this?
What are some histological features of this stage?
SUBACUTE
thickened epidermis
What stage of Eczematous Dermatitis is this?
What are some histological features of this stage?
CHRONIC
epidermis extends downwards into the dermal layer
Briefly describe the general mechanism underlying:
atopic dermatitis
allergic contact dermatitis
irritant contact dermatitis
ATOPIC Dermatitis - Eczema (infantile, childhood, constitutional, endogenous)
ALLERGIC Dermatitis - DTH-induced cell damage due against an allergen; subsequent exposures results in activation of adaptive immunity)
IRRITANT Dermatitis -** TLR-induced cell damage** develops upon FIRST exposure in most people via activation of Innate immune system
What are some characteristic features of atopic dermatitis?
who does it affect?
progression of disease?
what is the inheritance pattern?
what will these patients eventually develop?
- affects mostly young children (under 5), especially those with a genetic predisposition (70% have a family history of atopy)
- spontaneous improvement is expected, but relapses can occur
- inheritance is polygenic (clinically normal parents may have affected children and vice versa)
- 50-60% will develop asthma
What are 3 pathophysiological explanations as to why atopic dermatitis develops?
1) Cutaneous Problem
- filaggrin deficiency -> breakdown of skin integrity -> skin is more susceptible to allergens and infections -> which can initiate inflammation and pruritic reactions that cause the patient to scratch the skin (excoriation).
- Increased keratinization: Ichthyosis vulgaris, increased palmar linearity and keratosis pilaris (due to sweat retention, prickly heat)
- Defective water binding: Asteatosis (dry skin dermatitis, eczema craquelé)
2) Immunologic
- Increased ability to form IgE
- Increased production of IL-4, which correlate with increased IgE production
3) Neurovascular
- white dermographism - increased vasoconstrictor tone as a result of excess adenylate cyclase and phosphodiesterase activity -> decreased cAMP
- delayed blanch to cholinergic agents
What is the hygiene hypothesis?
What is the hapten hypothesis?
What disease are these two hypotheses in relation to?
hygiene hypothesis – lack of early exposure to various antigens may increase susceptibility to allergic diseases by suppressing the natural development of the immune system.
hapten hypothesis – rise in atopic dermatitis is caused by the revolutionary increase in exposure to chemical haptens in the personal environment
Both in relation to ATOPIC DERMATITIS
These 3 symptoms are very characteristic of a particular disease. What is it?
Bonus points if you know what these are called.
atopic dermatitis
features are due to increased keratinization:
- *top**: Ichthyosis vulgaris
- *middle**: increased palmar linearity
- *bottom:** keratosis pilaris (due to sweat retention, prickly heat)
This symptom is found in this particular skin disorder. What is it?
Bonus points if you kow what it’s called.
atopic dermatitis
white dermographism
What are the physical findings associated with atopic dermatitis?
- itching -> scratching, which produces most of the dermatitis
- dry and scaly skin
- Facial pallor, cool extremities, and white dermographism
- Ichthyosis vulgaris and keratosis pilaris are common associated disorders
- Atopic Diathesis – characterized by hyperpigmentation (black and blue shine) + Dennie’s lines (extra folds on lower eyelids)
- Pityriasis alba (dry, fine-scaled, pale patches on the face)
What is the atopic diathesis?
How do you know if one suffers from this? (2)
predisposition to develop one or more of hay fever, allergic rhinitis, bronchial asthma, or atopic dermatitis
Patients usually have hyperpigmentation (black and blue shine) + Dennie’s lines (extra folds on lower eyelids)
What are some of the factors that aggravate atopic dermatitis?
pathogens that can do the same?
- Antigens: foods (eggs, fish, milk, peanut, whweat) and inhalants (dust, pollens, dander)
- Sweating (hot baths, exercise, and strong emotional reactions)
- Dry skin (excessive bathing, decreased humidity)
- Wool Clothing
- Staphylococcal Aureus Infection
- Pityrosporon yeast
- Endocrine dysfunction
- Stress
What are some lab findings that you would expect in a patient with atopic dermatitis?
- 70% have a delayed blanch phenomenon with ACh injection
- Biopsy - shows acanthosis, epidermal edema (spongiosis), infiltration with lymphocytes, macrophages, plasma cells, and eosinophils (in other words, eczematous dermatitis)
- Moderate peripheral blood eosinophilia
- Rare positive patch test
- Food Allergy testing (in children)
What is this and what patients would normally present with this?
so..sexy….
…
Exfolitative Dermatitis (total body redness and scaling); is a complication of atopic dermatitis
What complications are associated with atopic dermatitis?
- Exfoliative dermatitis (total body redness and scaling)
- Cataracts
- Increased susceptibility to viral, bacterial, and fungal infections
- Staphylococcus aureus = common
- HSV or vaccinia virus
- Trichophyton rubrum = common
- common viruses (warts/molluscum)
- increased susceptiblility to infection by live-attenuated viruses.
- Short stature - chronic inflammation of the skin consumes much energy to fix the skin that the kid does not grow well
How do you treat Atopic Dermatitis?
- Control trigger stimuli (avoid activities that cause sweating, use cotton clothing, cool/ventilated environments, use mild soaps, avoid excessive bathing and drying of skin, lubrication, reduce stress)
- Corticosteroids
How does allergic dermatitis occur?
What are the general features of typical allergens?
Who does it generally affect?
DTH-induced cell damage due against an allergen; subsequent exposures results in activation of adaptive immunity)
Haptens are allergens of low MW, good lipid solubility, and chemical reactivity
generally affects those with a genetic predisposition
What is the typical presentation of allergic contact dermatits?
- erythema w. vesicles (bullae if reaction is severe)
- Intensely pruritic
- Distribution – distinct borders usually corresponds to site of exposure (usually with distinct borders) but may generalize; palms are rarely affected:
- LINEAR/STREAKY – for poison ivy
- ear lobes (nickel earrings)
- mustache (hair dye)
- Repeated contact results in reaction that are more rapid and severe.
- Severity is proportional to the duration of contact and concentration of the allergen (contactant); degree of sensitivity of the individual is also important.
What is the ID reaction?
What are some examples of this happening?
What type of skin disorder is this generally found in?
- *ID reaction -** allergen may begin in one place, but may generalize into systemic contact dermatitis.
- if a person has been sensitized to an allergen and is then exposed orally, the person may get dermatitis especially in moist areas (axilla, underwear line, perianal area.
Common example: someone who has been sensitized to poison ivy eat raw cashews and mangos because these cross-react with the same receptors!
Other example: Nickel and chromate also cross-react
Common in allergic dermatitis
What type of skin disorder is this? How can you tell?
Allergic contact dermatitis
can tell because the distribution is LINEAR and borders are DISTINCT
What type of skin disorder is this?
How can you tell?
Atopic dermatitis
1) he’s a child
2) generalized dry scaly skin
What type of skin disorder is this?
How can you tell?
ID reaction of allergic contact dermatitis
can tell because the dermatitis is in moist areas (axilla, underwear line, perianal area)
What increases sensitivity to allergic dermatitis?
pressure
friction
heat
H2O exposure (heat/sweat allows allergens to pass through clothes)
How is allergic dermatitis diagnosed?
- Patch testing
- Trial of avoidance
- both
How is allergic dermatitis treated?
- Avoidance of contactants/education
- Cold compresses
- Topical or systemic **corticosteroids
- Antihistamines
- Barrier creams**
What skin disorder is this normally associated with?
What are some of the defining features?
Irritant contact dermatitis
distribution - borders are usually indiscriminate; localized.
Red, pruritic, burning/stinging sensation
fissury look (classic presentation)
What is irritant contact dermatitis?
Who does it affect?
What are the typical irritants?
TLR-induced cell damage develops upon FIRST exposure in most people via activation of Innate immune system
affects anyone, but fair-skinned whites are more sensitive than darker skin individuals
Irritants can be:
- *Acute irritants** – sudden insult to skin; ex: acids/alkali/UV light
- *Chronic irritant** – require repeated or prolonged contact; ex: H2O, soaps, detergents, organic solvents
- Activate TLRs on keratinocytes
- Usually a high concentrations of contactant is required to set off reaction
How do you distinguish allergic contact dermatitis from an irritant contact dermatitis?
do a patch test
allergic = (+)
irritant = (-)
What increases one’s susceptibility to irritant dermatitis? (6)
- Cold, windy weather -> increases chapped skin (breaks in the skin that allow irritants to enter)
- decreased humidity -> same
- Friction/injury -> same
- increased temp (sweat) -> opens pores?
- Atopic history
- ** Age (very old/very young**)
How is irritant dermatitis diagnosed?
Trial of avoidance because patch test is usually NEGATIVE
How is irritant contact dermatitis treated?
- Protection via avoidance or reduction of heat, moisture, soaps, perspiration, friction, and pressure.
- corticosteroids
- Antihistamines for control of pruritus
What is the route of transmission for Scabies?
Where does it usually infect in adults? kids?
Where does the mite usually live on the body?
Does it consume blood?
Prolonged physical contact (venerally)
skin’s surface , esp in warm areas (palms and soles of feet, genital areas, flexor wrists, elbows, finger and toe webs, buttocks, breasts, waistline) The scalp is spared in adults.
In kids, lesions can occur on the scalp.
Female mite burrows very superficially into the epidermis (btwn stratum corneum and stratum granulosum), so that it can receive O2 via diffusion; NO blood consumption occurs
If you see this lesion on a kid, what infestation might he/she have?
scabies - they love the palms and soles of feet. Also note the linear lesion on the upper R
If you see this lesion, what might you think this person is infested with?
scabies - they love the palms and soles of feet. Also note the linear lesion on palm
What are characteristic skin findings on a person infested with scabies?
How would you diagnose and treat this person?
scabietic burrows (thread-like lesions) usually excoriated, resulting in crusted papules.
1˚ infection: eczematous dermatitis that is intensely pruritic, esp. at night; can lead to excoriation and 2˚ bacterial infection
Diagnose:
- Mites, ova, feces can be demonstrated in mineral oil scrapings of fresh papule or burrow.
- Ink test can also show site of burrow
- Biopsy - shows organism present very superficially in the epidermis.
- ELISA testing – patients have higher IgE levels
Treatment:
Elimiite (permethrin)
Lindane (neurotoxic)
Crotamiton (recommended for children/pregnant women)
Benzyl benzoate
Malathion
Sulfur
Ivermectin
What is this diagnostic of?
Scabies - organism present very superficially in the epidermis.
What are the 3 types of crabs infections?
How are they usually transmitted?
What do they require for survival?
- Pediculosis Capitis - close contact, shared hats, hair care articles(common in children, schools, day care centers)
- Pediculosis Corporis - disease of vagrants or persons with poor hygiene - transmitted by infected clothing or bedding (esp. on the seams of clothing)
- Pediculosis Pubis - close physical or sexual contact (other STD often evident), clothing, towels, bedding
- require blood meals from the host (compared to the scabies, which does not)
If you see lesions on the scalp, esp on the occipital scalp, what infestation might this person have?
What other symptoms and physical findings might this peron have?
How might you treat this person?
Pediculosis Capitis - they LOVE the scalp hair, especially of the occipital scalp
- Erythematous papular bites on scalp and neck.
- Pruritus
- Excoriations, with oozing and crust formation.
- Neck adenopathy
Treatments:
“if you don’t treat this, your head (capitus) will swell to the size of a BLiMP from the itchiness”
- Lindaine
- Malathion lotion (Ovide)
- Pyrethrin (RID) with piperonyl butoxide-containing shampoo.
- Bactrim – kills the commensal organisms present in lice gut, which kills the louse.
- Remove nits with a fine-toothed comb.
- Treat all close contacts and family members. Clean clothes and house
If you see lesions on the shoulders, interscapular areas, trunk or buttocks, what infestation might this person have?
What other symptoms and physical findings might this peron have?
How might you treat this person?
Pediculosis Corporis
With long-standing infestation, can see
- crusted, eczematous dermatitis
- thickened, dry, scaling, hyperkeratotic, hyperpigmented skin.
- 2˚ bacterial infection frequently occurs.
Treatment:
“You’d never want to kiss a bum (dirty clothing) on the LiP”
- Pyrethrums-sprayed onto clothing (tick repellent)
- Lindaine treatment for clothing
If you see lesions on the pubic hair, what infestation might this person have?
What other symptoms and physical findings might this peron have?
How might you treat this person?
Pediculosis Pubis
Symptoms/Findings
- Itching in the pubic area
- Excoriations
- maculae cerulea (steel gray macules).
- Lice may be seen as small brownish organisms on pubic hair or surrounding skin.
1˚ changes are due to pruritus and scratching.
2˚ infection is uncommon
Treatment:
“Puting your LiP Everywhere down there (pubis) is just a bad, bad idea…”
- Elimiite (Permethrin)
- Lindane
- Pyrethrin with piperonyl butoxide-containing shampoo
- All sexual contacts should be treated.
