Updated: 12/16/2021

Contact Dermatitis

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  • Snapshot
    • A 17-year-old girl presents to her primary care physician with symmetric swollen eyes. On further questioning, she reveals that she recently changed her brand of eye shadow. On exam, only her upper eyelids are erythematous with vesicles. She is instructed to stop the eyeshadow immediately. Given the sensitive nature of eyelids, she is given petroleum jelly to soothe the contact dermatitis. She is reassured that this will resolve.
  • Introduction
    • Clinical definition
      • erythematous and pruritic rash caused by cutaneous exposure
        • to allergens
          • most common form of contact dermatitis
        • to irritants
          • often involves hands
          • often from occupational exposures
  • Epidemiology
    • Demographics
      • female > male
    • Risk factors
      • exposure to potential allergens or irritants
      • occupations with higher risk of contact dermatitis
        • healthcare
        • food production
        • cosmetics
        • farming
  • Etiology
    • Pathogenesis
      • allergic contact dermatitis
        • immunologic reaction to allergen causing type IV hypersensitivity reaction
        • delayed T-cell mediated reaction
        • activation of Th1 cells
        • memory CD4+ cells are created and dermatitis develops upon re-exposure or cross-reaction
      • irritant contact dermatitis
        • nonimmunologic reaction to substance that causes direct damage to the skin
        • release of inflammatory cytokines activated by non-immune pathways
    • Most common allergens include
      • poison ivy
      • poison oak
      • poison sumac
    • Most common irritants include
      • chemicals
      • alcohol
      • creams
  • Presentation
    • Symptoms
      • presents 12-48 hours after exposure to allergen
      • presents minutes to hours after exposure to irritant
      • pruritic
      • burning or stinging
    • Physical exam
      • linear or geometric rash, corresponding to topical exposure, composed of papules and vesicles
        • can progress to blisters and bullae
        • for example, patients allergic to the adhesive in a bandaid will present with a square or rectangular-shaped rash
      • eczematous rash
        • lichenification
        • fissuring
        • scaling
  • Studies
    • Labs
      • none
    • Patch testing
      • to identify potential allergens
      • to help prevent future exposures
    • Histology
      • spongiosis
  • Differential
    • Atopic dermatitis
  • Treatment
    • Conservative
      • skin moisturizer
        • indication
          • decrease irritation in nonimmunologic contact dermatitis
    • Medical
      • topical corticosteroids
        • indication
          • localized or mild-to-moderate disease
          • first-line therapy
      • topical tacrolimus
        • indication
          • when corticosteroids are contraindicated
      • systemic corticosteroids
        • indications
          • widespread or severe disease
          • disease that involves mucosa
  • Comlications
    • Postinflammatory hypo- or hyperpigmentation
    • Secondary bacterial infection
  • Prognosis
    • Typically resolves with treatment
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(M2.DM.17.4769) A 25-year-old woman with no prior medical history presents with complaints of a new skin rash. She was in her usual state of health until one month ago when she began developing an itchy rash on her lower abdomen. The patient works as a fitness instructor. Her family history is notable for a father with psoriasis and a brother with atopic dermatitis. Physical exam is notable for an otherwise healthy-appearing female and Figure A on skin exam. Her temperature is 98.9°F (37.2° C), pulse is 80/min, blood pressure is 120/82 mmHg, respirations are 10/min, and O2 saturation is 99% on room air. Her laboratory results are as follows:

Serum:
Na+: 135 mEq/L
K+: 4.2 mEq/L
HCO3-: 25 mEq/L
Cl-: 100 mEq/L
BUN: 19 mg/dL
Creatinine: 1.0 mg/dL
Glucose: 94 mg/dL

Hemoglobin: 14.4 g/dL
Leukocyte count: 10,000 cells/mm^3
Platelet count: 380,000/mm^3

Which of the following is the mechanism underlying this patient’s skin findings?

QID: 109137
FIGURES:
1

IgE-mediated hypersensitivity

18%

(5/28)

2

Immune complex-mediated hypersensitivity

4%

(1/28)

3

T-cell-mediated hypersensitivity

61%

(17/28)

4

Fungal infection

11%

(3/28)

5

Deficiency of filaggrin

7%

(2/28)

M 5 D

Select Answer to see Preferred Response

(M2.DM.14.25) A 20-year-old man presents to his primary care physician complaining of intense itching on the back of his left calf. He states that he noticed a red and blistering rash this morning and does not recall experiencing a similar rash in the past. His social history is notable for a job at the zoo. His temperature is 97.7°F (36.5°C), blood pressure is 120/74 mmHg, pulse is 70/min, respirations are 14/min, and oxygen saturation is 98% on room air. His physical exam is notable for the finding in Figure A. Which of the following findings would be found in the most likely diagnosis?

QID: 103818
FIGURES:
1

Acanthosis

49%

(51/104)

2

Caseating granulomas

1%

(1/104)

3

Extraepidermal vesicles with keratinocytes

8%

(8/104)

4

Langerhans giant cells

8%

(8/104)

5

Spongiosis

33%

(34/104)

M 5 E

Select Answer to see Preferred Response

Evidence (4)
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