Photobiology, Photodermatoses and Sunscreen Flashcards
What is the most common skin disorder provoked by sun exposure
Polymorphic Light Eruption (PMLE)
What skin disorders can be diagnosed by photoprovocation?
List 3
- Polymorphic Light Eruption (PMLE)
- Actinic prurigo
- Actinic folliculitis
- Solar urticaria
- Chronic actinic dermatitis
- Juvenile spring eruption
- Hydroa vacciniforme
What lab investigations should be performed to evaluate photodermatoses?
List 3
- ANA
- ENA
- dsDNA
- Porphyria screen (feces, RBCs, urine)
What are photopatch testings performed for?
Suspected contact dermatitis to a substance occurring onliy in the presence of sunlight (sunscreen/NSAIDs)
List 3 benefits of UV
- Production of Vitamin D (moderate exposure)
- Regulates calcium metabolism, insulin secretion, BP, immunity and cell propagation
- Improvement in mood
- Increase in energy
- Treatment of dermatological conditions
- Inflammatory skin conditions
- Vitiligo
- CTCL
- Granuloma annulare
What is a photosensitizer?
A chemical or drug that induces a photodermatosis
What is a photodermatosis called that is eczematous?
Photodermiatitis
What is a phototoxic reaction?
Exaggerated sunburn-like reaction without an immune response due to a drug or chemical
What is a photo exacerbated reaction?
List 5 examples.
An underlying skin condition worsening due to UV light
- Lupus erythematosus
- Dermatomyositis
- Darier disease
- Rosacea
- Pemphigus vulgaris
- Pemphigus foliaceus
- Atopic dermatitis
- Psoriasis
List 5 clues of photosensitivity
- Exacerbated in summer
- Sharp cut-off between affected area and skin covered by clothing/jewelry
- Sparing of:
- Folds of upper eyelids
- Deep furrows on face/neck
- Skin covered by hair
- Skin shadowed by ears, under nose and under chin
- Sparing of web spaces between fingers
List 3 phototoxic/allergic reactions caused by external photosensitizers
- Drug-induced photosensitivity
- Thiazides
- Tetracyclines
- NSAIDs
- Phenothiazines
- Voriconazole
- Quinine
- Vemurafenib (EGFRi)
- Photocontact dermatitis
- Due to phototoxic chemicals
- Psoralens in plants, vegetables, fruit
- Fragrances in cosmetics
- Sunscreen chemicals
- Dyes and disinfectants
- Due to phototoxic chemicals
- Pseudoporphyria
- Induced by drugs +/- renal insufficiency
List 2 genetic photodermatoses
- Xeroderma pigmentosum
- defect in DNA repair
- Bloom syndrome
- Autosomal recessive
- Short stature
- Telangiectasia
- Rothmund Thomson syndrome
- Autosomal recessive
- Poikiloderma
- Cockayne syndrome
- Autosomal recessive
- Neurodegenerative disorder
What is the most common form of porphyria?
What causes porphyria?
What systems are affected by porphyria?
Porphyria cutanea tarda
Impairment in the process that makes heme
- Cutaneous - blistering, scarring, photodermatitis
- GI - Abdominal pain/cramping, vomiting, constipation
- CNS - seizures, mental disturbances, nerve damage
- MSK - muscle pain, weakness or paralysis
- GU - urine can turn red/brown
Name this dermatological diagnosis
Polymorphic light eruption (PMLE)
Who is typically most affected by polymorphic drug eruption (PMLE)?
What type of reaction is PMLE?
How to prevent PMLE?
Young, adult women (20-40s)
Delayed hypersensitivity reaction to a compound in the skin altered by exposure to UV radiation
- Cover affected areas with UPF clothing or densely woven sun protective clothing
- Stay in the shade
- Apply SPF 50 frequently to all uncovered skin
- Fake tan (SPF 2)
- UVB desensitization
- Emergency oral steroids (5 days)/topical steroids for flare while on holiday
- Antihistamines pre exposure
- Slow introduction to UV exposure in spring/summer months
Name this dermatological diagnosis that occurred within 15 minutes of being in the sun and disappeared upon returning indoors
What forms are more difficult to treat?
Solar urticaria
UVA and visible light
Name this dermatological diagnosis
Who is most commonly affected by this presentation?
What is the characteristic feature?
What concerning diagnosis looks similar on histology?
Chronic actinic dermatitis
Men >50yo
Severely itchy, thickened dry skin in areas exposed to sunlight
Cutaneous T-cell lymphoma
What is the recommended investigations for suspected chronic actinic dermatitis?
What is the recommended treatment?
- Determine wavelength - phototesting
- Determine possible trigger (75%) - skin patch testing
Treatment
- Emollients
- Topical steroids
- TCIs
- Emergency systemic steroids (if really uncomfortable)
- AZA
- Cyclosporin
- UV desensitization with steroid cover
- Lifelong sun avoidance and avoidance of allergens
Name this dermatological diagnosis
Who commonly presents with this diagnosis?
What is the recommended treatment?
Juvenile Spring Eruption
Young boys with short hair
- Topical steroids
- Emollients
- Antihistamines
Name this dermatological diagnosis
What is the typical presentation?
What is the affected gene?
What populations is it most commonly seen?
Actinic prurigo
- Intensely itchy papules on sun-exposed sites (in long-standing cases can be on skin covered by clothing).
- Lips are involved in 60-70%
- Conjunctiva affected in 45%
HLA DRB1* 0407
Indigenous or Latin American, 1/3 prepubertal M=F, later onset F>M
What treatment options are available for actinic prurigo?
- Sun avoidance
- Emollients
- Topical corticosteroids
- Antimalarials (hydroxychloroquine)
- Thalidomide
Name this dermatologic diagnosis
Hydroa Vacciniforme
What is the most common trigger of hydroa vacciniforme (HV)?
What is the clinical presentation of HV?
What age group does it tend to affect?
What is an associated virus and what is the concern?
UVA
Recurrent fluid-filled blisters that heal with pox-like scars
3-15yo, F>M
EBV, severe forms can result in fatal lymphoma
What are treatment strategies for hydroa vacciniforme?
- Sun avoidance
- Physical sunscreen
- Protective clothing
- Antimalarials
- UVB desensitization
How does a physical sunscreen work and what are possible active ingredients?
How does a chemical sunscreen work and what are possible active ingredients?
Like a shield on the surface of the skin to deflect the sun’s rays
Zinc oxide +/or Titanium dioxide
Like a sponge absorbing the sun’s rays
Oxybenzone, Avobenzone, Octocrylene, Homosalate, Octisalate
