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Photosensitive Dermatitis

»	What is the definition of photosensitivity?
»	What is the difference between a phototoxic reaction and a photoallergic reaction?
»	What is the clinical appearance of a photodistributed eruption?
»	Name some of the most common topical phototoxic and photoallergic agents and their action spectrums.
»	Name some of the most common systemic phototoxic and photoallergic agents and their action spectrums.
»	Give some examples of unique phototoxic reactions.
»	What are some scenarios in which the skin may be more sensitive to ultraviolet radiation?
»	What are the important questions to ask a patient with suspected photosensitivity?
»	What are the most common causes of photosensitive dermatoses?
»	What is persistent light reactivity?
»	What is polymorphous light eruption (PMLE)?
»	How is PMLE diagnosed?
»	How is PMLE treated?
»	What is actinic prurigo?
»	What is solar urticaria?
»	Discuss the differential diagnosis of photodermatoses in infants or young children.
»	How do hydroa aestivale and hydroa vacciniforme differ?
»	Which porphyrias are associated with photodermatoses?
»	Describe the cutaneous changes in porphyria cutanea tarda.
»	What causes porphyria cutanea tarda?
»	How is porphyria cutanea tarda diagnosed?
»	How is variegate porphyria distinguished from porphyria cutanea tarda?
»	What treatments are used in porphyria cutanea tarda?
»	What are the cutaneous findings in erythropoietic protoporphyria?
»	How is a diagnosis of erythropoietic protoporphyria made?
»	What treatments are used in erythropoietic protoporphyria?
»	Do any other medical problems occur in patients with erythropoietic protoporphyria?
»	Name some other photorelated disorders.

What are some scenarios in which the skin may be more sensitive to ultraviolet radiation?

Isotretinoin and retinoids (thinning of the stratum corneum)
5-Fluorouracil (5-FU) (antimetabolite affecting DNA repair)
Methotrexate (MTX) (antimetabolite affecting enzymatic recovery after UV damage)
Postprocedure (peels, resurfacing, dermabrasion, etc.) causing thinning of the stratum corneum and increased keratinocyte turnover