Skin Disorders due to the Environment

Question 1

Answer 1

Polymorphic Light Eruption

• most common photodermatosis
• UVA> UVB
• presents in early spring or summer
• within several hours to days (NOT <30 min) after first exposure to intense dose of sunlight
• pruritus can be first symptom
• can have systemic sxs but rare ( fever, headache, chills and nausea)
• Diagnosis:
  
  • ddx: lupus → check ANA, dsDNA, anti-SSA/Ro, or anti-SSB/la
  • skin biopsy can be helpful but not diagnostic
• tx:
  
  • sun protection
  • topical steroids
  • antihistamins
  • oral low dose steroid for moderate/severe cases
  • photohardening for 2-3x/week for 4-6 weeks
  • hydroxychloroquine for severe cases

Question 2

Answer 2

• Phototoxicity
• drug rxn to medication= requires exposure to drug and UVR (UVA> UVB)
• **DOES NOT INVOLVE IMMUNE RESPONSE**
• burning/tingling sensation on exposed areas
• only distributed on sun-exposed skin
• resembles sun-burn or blisters**
• erythema and edema may appear within hours
• diagnosis:
  
  • pt hx
  • photodistributed eruption
  • biopsy
• tx:
  
  • avoid medication or sun
  • topical/oral steroids
  • cool compresses

Question 3

Answer 3

Phytophotodermatitis

• from plants that contain psoralen compounds**
• same as phototoxicity but with exposure to plants andUVR

**DOES NOT INVOLVE IMMUNE RESPONSE**

• burning/tingling sensation on exposed areas
• only distributed on sun-exposed skin
• resembles sun-burn or blisters**
• erythema and edema may appear within hours
• diagnosis:
  
  • pt hx
  • photodistributed eruption
  • biopsy
• tx:
  
  • avoid medication or sun
  • topical/oral steroids
  • cool compresses

Question 4

Photoallergy

Answer 4

• delayed type I hypersensitivity rxn
• requires photoallergen and UVR exposure
  
  • reqyire more than one exposure
• resembles atopic dermatitis
• may spread beyond the sun exposed skin
• diagnosis:
  
  • clinical and hx
• tx:
  
  • avoid the drug and sun protection
  • topical/oral steroids (depending on severity)