Photodermatoses/Mucocutaneous Rxns Flashcards
Definition of Photosensitivity
abnormal response to UV radiation or visible light that underlies many skin conditions (called photodermatoses)
How is diagnosis of photosensitivity determined?
- Primarily from the history & physical exam
- Occasionally a skin biopsy
Definition of Sunburn?
Exposure to excessive UVA and UVB light, causing an inflammatory response in the skin
Clinical manifestations of Sunburn?
- painful erythema
- blistering
Timeline of Sunburn?
- Erythema at 3-5 hours following exposure
- peaks at 12-24 hours
- subsides at 72 hours
Prevention of sunburn?
- limit sun exposure during summer months b/w 10am-4pm
- protective clothing
- broad spectrum sunscreens at least 30 SPF
- Reapply sunscreen every 2 hours
- infants <6 months should avoid sun exposure
Treatment for sunburn?
- self-limiting
- may require hospitalization if severe blistering
- topical agents (aloe vera, etc)
- cool compresses
- Oral OTC analgesics
Definition of Polymorphous Light Eruption (PMLE)?
“sun poisoning” or “sun allergy” - a specific photo rash
Clinical manifestations of Polymorphous Light Eruption?
- Papulonodular lesions, symmetrically distributed on sun-exposed skin
- Pruritic
- Angular chelitis
Treatment of Polymorphous Light Eruption?
- sun protection/avoidance
- topical corticosteroids
- oral corticosteroids
- phototherapy
What is one possible cause of Polymorphous Light Eruption?
There is a genetic component to it!
Cause of Phototoxicity?
cellular damage following sun exposure when taking a precipitating compound
Examples of precipitating compounds that cause Phototoxicity?
-Tetracyclines (Doxy)
-Thiazides
- Sulfonamides
- NSAIDS
- Griseofulvin
- Tar compounds
- Phenothiazides
- St. Johns Wort
Endogenous causes of phototoxicity?
- SLE (lupus)
- Porphyria (blood disorder)
- Dermatomyositis (inflamm. disorder)
Clinical manifestations of phototoxicity?
appears as exaggerated sunburn
2 types of Mucocutaneous Reactions
- Stevens-Johnson Syndrome
- Toxic Epidermal Necrolysis
Characteristics of Stevens-Johnson Syndrome?
- Dermatologic Emergency
- Skin detachment <10% of the body surface area
- mucous membranes are affected in >90% of patients
- usually 2 different mucous membrane sites at once:
- ocular, oral, or genital
Characteristics of Toxic Epidermal Necrolysis
- Dermatologic Emergency
- Same as SJS but more severe
- Detachment of >30% of body surface area
What essentially is happening with SJS/TEN?
WORST DRUG ALLERGY EVER
Clinical manifestations of SJS/TEN?
- begins with prodrome of fever & flu-like symptoms 1-3 days before skin eruption
- coalescing erythematous macules
- vesicles and bullae on skin & mucous membranes
- finally, skin sloughing
Lesion course in SJS/TEN?
- on face and trunk
- spread rapidly, palms and soles become painful, erythematous, edematous
-
Test that determines SJS/TEN?
-Positive Nikolsky sign
(Gentle pressure rubbed on the skin results in the formation of a blister)
-no connection between epidermis and dermis
Medication triggers for SJS/TEN?
- This is the most common cause of SJS/TEN
- allopurinol
- anticonvulsants
- sulfonamides
- NSAIDS
Infections that can trigger SJS/TEN?
- Mycoplasma
- CMV (cytalomegalovirus)
Complications of SJS/TEN?
- shock
- hypertension
- renal failure
- respiratory failure
- corneal ulcerations
- ocular scarring/blindness
- vulvovaginitis/balanitis
Steps to take if develop SJS/TEN?
- Discontinue causative agent
- referral to a burn center
- treatment similar to major burn
- fluid resuscitation, wound care, prevention/treatment of infection
