2/17 Dermatitis (Atopic, Contact, and Infestations)

Question 1

What is the difference between Dermatosis and Dermatitis and Eczematous dermatitis?

Answer 1

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)

Question 2

What stage of Eczematous Dermatitis is this?

What are some clinical features of this stage?

Answer 2

ACUTE

Erythema
Edema
Vesicles/bulla (serum in the epidermis) - hallmark feature
Oozing (serum reaching the epidermal surface)

Question 3

What stage of Eczematous Dermatitis is this?

What are some clinical features of this stage?

Answer 3

Sub-acute

Crust
Scales

Question 4

What stage of Eczematous Dermatitis is this?

What are some clinical features of this stage?

Answer 4

Chronic

Lichenification
Hyper/hypo-pigmentation

Question 5

What stage of Eczematous Dermatitis is this?

What are some clinical features of this stage?

Answer 5

Chronic

Lichenification
Hyper/hypopigmentation

Question 6

What stage of Eczematous Dermatitis is this?

What are some histological features of this stage?

Answer 6

ACUTE

Vesicles in the epidermis + EDEMA + keratinocytes cells floating around

spongiosis = pathological hallmark

Question 7

What stage of Eczematous Dermatitis is this?

What are some histological features of this stage?

Answer 7

SUBACUTE

thickened epidermis

Question 8

What stage of Eczematous Dermatitis is this?

What are some histological features of this stage?

Answer 8

CHRONIC

epidermis extends downwards into the dermal layer

Question 9

Briefly describe the general mechanism underlying:

atopic dermatitis

allergic contact dermatitis

irritant contact dermatitis

Answer 9

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

Question 10

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?

Answer 10

• 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

Question 11

What are 3 pathophysiological explanations as to why atopic dermatitis develops?

Answer 11

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

Question 12

What is the hygiene hypothesis?

What is the hapten hypothesis?

What disease are these two hypotheses in relation to?

Answer 12

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

Question 13

These 3 symptoms are very characteristic of a particular disease. What is it?

Bonus points if you know what these are called.

Answer 13

atopic dermatitis

features are due to increased keratinization:

• *top**: Ichthyosis vulgaris
• *middle**: increased palmar linearity
• *bottom:** keratosis pilaris (due to sweat retention, prickly heat)

Question 14

This symptom is found in this particular skin disorder. What is it?

Bonus points if you kow what it’s called.

Answer 14

atopic dermatitis

white dermographism

Question 15

What are the physical findings associated with atopic dermatitis?

Answer 15

• 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)

Question 16

What is the atopic diathesis?

How do you know if one suffers from this? (2)

Answer 16

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)

Question 17

What are some of the factors that aggravate atopic dermatitis?

pathogens that can do the same?

Answer 17

• 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

Question 18

What are some lab findings that you would expect in a patient with atopic dermatitis?

Answer 18

• 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)

Question 19

What is this and what patients would normally present with this?

Answer 19

so..sexy….

…

Exfolitative Dermatitis (total body redness and scaling); is a complication of atopic dermatitis

Question 20

What complications are associated with atopic dermatitis?

Answer 20

• 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

Question 21

How do you treat Atopic Dermatitis?

Answer 21

• 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

Question 22

How does allergic dermatitis occur?

What are the general features of typical allergens?

Who does it generally affect?

Answer 22

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

Question 23

What is the typical presentation of allergic contact dermatits?

Answer 23

• 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.

Question 24

What is the ID reaction?

What are some examples of this happening?

What type of skin disorder is this generally found in?

Answer 24

• *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

Question 25

What type of skin disorder is this? How can you tell?

Answer 25

Allergic contact dermatitis can tell because the distribution is LINEAR and borders are DISTINCT

Question 26

What type of skin disorder is this? How can you tell?

Answer 26

Atopic dermatitis 1) he's a child 2) generalized dry scaly skin

Question 27

What type of skin disorder is this? How can you tell?

Answer 27

ID reaction of allergic contact dermatitis can tell because the dermatitis is in moist areas (axilla, underwear line, perianal area)

Question 28

What increases sensitivity to allergic dermatitis?

Answer 28

pressure friction heat H2O exposure (heat/sweat allows allergens to pass through clothes)

Question 29

How is allergic dermatitis diagnosed?

Answer 29

- Patch testing - Trial of avoidance - both

Question 30

How is allergic dermatitis treated?

Answer 30

- Avoidance of contactants/education - Cold compresses - Topical or systemic **corticosteroids - Antihistamines - Barrier creams**

Question 31

What skin disorder is this normally associated with? What are some of the defining features?

Answer 31

Irritant contact dermatitis distribution - borders are usually **indiscriminate; localized.** Red, pruritic, **burning/stinging** sensation fissury look (classic presentation)

Question 32

What is irritant contact dermatitis? Who does it affect? What are the typical irritants?

Answer 32

**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

Question 33

How do you distinguish allergic contact dermatitis from an irritant contact dermatitis?

Answer 33

do a patch test allergic = (+) irritant = (-)

Question 34

What increases one's susceptibility to irritant dermatitis? (6)

Answer 34

* 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**)

Question 35

How is irritant dermatitis diagnosed?

Answer 35

Trial of avoidance because patch test is usually **_NEGATIVE_**

Question 36

How is irritant contact dermatitis treated?

Answer 36

- **Protection via avoidance or reduction** of heat, moisture, soaps, perspiration, friction, and pressure. - **corticosteroids** - **Antihistamines** for control of pruritus

Question 37

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?

Answer 37

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_**

Question 38

If you see this lesion on a kid, what infestation might he/she have?

Answer 38

scabies - they love the palms and soles of feet. Also note the linear lesion on the upper R

Question 39

If you see this lesion, what might you think this person is infested with?

Answer 39

scabies - they love the palms and soles of feet. Also note the linear lesion on palm

Question 40

What are characteristic skin findings on a person infested with scabies? How would you diagnose and treat this person?

Answer 40

**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: 1. Mites, ova, feces can be demonstrated in **mineral oil scrapings** of fresh papule or burrow. 2. **Ink test** can also show site of burrow 3. **Biopsy** - shows organism present very superficially in the epidermis. 4. **ELISA testing** – patients have higher IgE levels Treatment: Elimiite (permethrin) Lindane (neurotoxic) Crotamiton (recommended for children/pregnant women) Benzyl benzoate Malathion Sulfur
 Ivermectin

Question 41

What is this diagnostic of?

Answer 41

Scabies - organism present very superficially in the epidermis.

Question 42

What are the 3 types of crabs infections? How are they usually transmitted? What do they require for survival?

Answer 42

* 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)

Question 43

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?

Answer 43

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

Question 44

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?

Answer 44

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

Question 45

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?

Answer 45

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 E**verywhere **down there (pubis)** is just a bad, bad idea..." * Elimiite (Permethrin) * Lindane * Pyrethrin with piperonyl butoxide-containing shampoo * All sexual contacts should be treated.