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Q5 Dermatology > Contact Dermatitis > Flashcards

Contact Dermatitis Flashcards

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Dermatology Board Prep flashcards
1
Q

dermatitis or eczema derinition

A

pattern of cutaneous inflammation that presents with:
ACUTE PHASE: erythema, vesiculation & pruritis

CHRONIC PHASE characterized by dryness, scaling,lichenification, fissuring & pruritis

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2
Q

Types of dermatitis (5)

A

many types, including

  1. Seborrheic
  2. atobic
  3. dyshidrotic
  4. nummular
  5. CONTACT DERMATITIS
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3
Q

Contact dermatitis:
definition
types

A

skin condition created by a reaction to an externally applied substance

2 types of contact dermatitis:

  • IRRITANT contact dermatitis (ICD)
  • ALLERGIC contact dermatitis (ACD)
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4
Q

When does allergic contact dermatitis occur?

A

ACD occurs when contact w/a substance elicits a DELAYED hypersensitivity reaction

SENSITIZATION process requires 10-14 days

re-exposure dermatitis appears w/in 12-48h

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5
Q

Most common cause of allergic dermatitis

A

Rhus dermatitis from:

poison ivy, poison oak, or poison sumac (all contain the resin urushiol)

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6
Q

Other common causes of allergic contact dermatitis (8)

A
  1. Fragrances
  2. Formaldehyde
  3. Preservatices
  4. Topic antibiotics
  5. Benzocaine
  6. Vitamin E
  7. Rubber compounds
  8. Nickel
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7
Q

Main sx of allergic contact dermatitis

A

PRURITIS (itching)

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8
Q

Allergic contact dermatitis presentation

A

eczematous, scaly edematous plaques with vesiculation distributed in areas of exposure

ACD is bilateral IF the exposure is bilateral (e.g. shoes, gloves, ingredients in creams, etc.)

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9
Q

Poison oak leaves (U) characteristics

A
  • 3-7cm
  • lobulated notched edges
  • groups of 3,5 or 7
  • grows on bush like plants
  • turn colors in autumn
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10
Q

Poison ivy leaves (U) characteristics

A
  • 3-15cm in length
  • notched edges
  • groups of 3s
  • grows on hairy-stemmed vines or low shrubs
  • turn colors in autumn
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11
Q

Rhus allergy typical presentation:

  • initial
  • subsequent
A

INITIAL episode:

  • occurs 7-10d after exposure
  • lasts longest (up to 6 weeks)

SUBSEQUENT outbreaks:

  • may appear within hours, (U) within 2 days
  • Rhus dermatitis lasts from 10-21 days depending on the severity
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12
Q

Rhus allergy appearance

A
  • lesions begin as erythematous macules that become papules or plaques
  • blisters often form over 1-2d
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13
Q

Rhus dermatitis what aids in dx?

A

linear streaks aid in dx (from the linear contact of the plant)

fomites can be contaminated by the plant oil lead to recurrent eruptions

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14
Q

Rhus dermatitis tx: most patients

A

most patient need MINOR supportive care:

  1. topical steroids for local involvement
  2. topical or oral antihistamines for pruritis
  3. oatmeal soaks/calamine lotion may soothe weeping erosions
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15
Q

Rhus dermatitis: severe involvement tx

A

may require oral steroids
-in cases of failing potent topical steroids or widespread

IF GIVEN FOR LESS THAN 2-3 WEEKS, PTS may relapse
so DO NOT GIVE SHORT BURSTS of steroids

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16
Q

Rhus allergy prevention (3)

A
  1. avoid the plants
  2. wash clothing, shoes & objects after exposure (within 10 mins if possible)
  3. apply barrier: clothing, OTC produces which bind resin more than skin
17
Q

Eyelid allergic contact dermatitis:
description
cause(s)

A

intensely pruritic
scaling red plaques on UPPER>lower eyelids

often caused by transfer from the hands
(C) causes: nail adhesive/polish, fragrances & preservatives in cosmetics, nickel

18
Q

evaluation of dermatitis

A
  1. comprehensive hx
  2. complete derm assessment of pt
  3. shape, configuration & location of dermatitis are useful clues to ID culprit
  4. elimination of suspected trigger may be both dx & therapeutic
  5. in chronic cases, PATCH TESTING is necessary to ID specific allergens
19
Q

What testing is necessary to identify specific allergens in chronic dermatitis?

A

patch testing

20
Q

Hx: what to ask in addition to dermatitis-specific hx (4)

A
  1. daily skin care routine
  2. all topical produces
  3. occupation/hobbies
  4. regular & occasional exposures (e.g. lawn care products, animal shampoos)
21
Q

Pt has allergic contact dermatitis. In addition to avoiding the allergen, what tx would you recommend?

A

Desonide cream (for a limited period: twice daily for 1 week, followed by once daily for 1-2 weeks, then d/c)

22
Q

Class 1, 2 or 3 steroid negative effects

A

regular use->steroid atrophy (thinning & easy bruising/purpura) & hypopigmentation in darker sking types

23
Q

Which steroids to use on the face?

A

class 6,7 steroids (e.g. desonide) can safely be used intermittently during flares

if topical steroids are used on the eyelid for more than one month, refer to an ophthalmologist for monitoring of intraocular pressure & the development of cataracts

24
Q

Patch testing:
use
process

A

used to determine which allergens a pt w/allergic contact dermatitis reacts against

series of allergens are applied to the back & removed after 2 days

on day 4 or 5, patient returns for results

+ rxns show erythema & papules or vesicles
ID of allergens helps pt find products free of those alergens

25
Q

When to refer allergic dermatitis pts for patch testing?

Positive reaction on patch testing indicates?

A

when allergen is unclear or the dermatitis is chronic

+ rxn DOES NOT mean pts rash is due to that allergen; elimination of the rash with removal of allergen confirms the clinical relevance of the positive patch test

26
Q

Treatment of ACUTE phase of allergic contact dermatitis

A

depends on severity of dermatitis:

  1. MILD-MOD cases: topical steroids of MED-STRONG potency for a limited course
  2. short course of systemic steroids may be required for acute flares
  3. oatmeal baths or soothing lotions can provide further relief in mild cases
  4. wet dressings help when there are extensive oozing & crusting
27
Q

Which allergic contact dermatitis cases should be referred to a dermatologist?

A

CHRONIC cases
or
pts w/dermatitis involving OVER 10% of BSA

28
Q

What is the 2nd most common allergic contact dermatitis?

A

NICKEL DERMATITIS

2nd to Rhus dermatitis

29
Q

Latex allergy presentation

A

either delayed or immediate hypersensitivity:
DELAYED HYPERSENSITIVITY: pts develop an allergic contact dermatitis, often presents on dorsal surface of the hands

IMMEDIATE HYPERSENSITIVITY: immediate sxs such as burning, stinking or itching with or without localized urticarial on contact w/latex proteins
-may include disseminated urticarial, allergic rhinitis and/or anaphylaxis

30
Q

Irritant contact dermatitis: definition

A

inflammatory rxn in skin resulting from exposure to a substance that can cause an eruption in most ppl who come in contact with it
-no previous exposure is necessary
-may occur from a single application w/severely toxic substances
but most commonly results from mildy irritating substances (e.g., soaps, detergents)

31
Q

Irritant contact dermatitis influencing factors (2 main categories)

A

a multifactorial dz where both exogenous (irritant & environmental) & endogenous (host) elements play a role

32
Q

most important exogenous factor influencing irritant contact dermatitis

A

inherent toxicity of the chemical for human skin

33
Q

2 endogenous factors influencing irritant contact dermatitis

A
  1. site differences in barrier fxn, making the face, neck, scrotum & dorsal hands more susceptible
  2. ATOPIC DERMATITIS is a MAJOR RISK FACTOR for irritant hand dermatitis b/c of impaired barrier fxn and lower threshold for skin irritation
34
Q

Irritant Clinical Dermatitis: Clinical Findings

A

mild irritants produce erythema, chapped skin, dryness & fissuring after repeated exposures over time

  • PRURITIS can range from mild to extreme
  • PAIN (C) symptom when erosions & fissures are present
  • severe cases present w/EDEMA, EXUDATE & TENDERNESS
  • potent irritants produce painful bullae within hours after exposure
35
Q

Irritant Contact Dermatitis evaluation & tx

A
  1. mainstay tx: ID & avoid potential irritant
  2. topical steroids to reduce inflammation & emollients to improve barrier repair (U) recommended
  3. refer to derm for pts not improving w/removal of irritant or in severe cases
  4. PATCH testing in occupational cases w/suspected chronic irritant dermatitis TO EXCLUDE ALLERGIC CONTACT DERMATITIS
36
Q

Irritant contact dermatitis prevention

A
  1. once causal irritant is identified, educate pts abt irritant avoidance, including everyday practices that may CAUSE or CONTRIBUTE to ICD
  2. use personal protective equipment (eg protective gloves for any wet work
  3. instead of soap, use less irritating substances such as emollients & soap substitutes when washing
  4. be careful for several months after dermatitis heals b/c skin remains vulnerable to flares of dermatitis for a long time

Q5 Dermatology (14 decks)

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