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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.

Name some of the most common topical phototoxic and photoallergic agents and their action spectrums.

The action spectrum for almost all topical phototoxic and photoallergic reactions is UVA, rarely UVB and visible light. Some of the most common topical agents are listed in Table 17-1.

Table 17-1. Topical Agents Causing Phototoxic and Photoallergic Reactions
	PHOTOTOXIC CHEMICALS	PHOTOALLERGIC CHEMICALS
	Benzocaine Benzoyl peroxide (UVB) Coal tar Erythromycin Halogenated salicylanilides Hydrocortisone Ketoprofen Porphyrins (visible light and UVB) Psoralens	Sunscreens: oxybenzone, benzophenone, etc. Fragrances: methylcoumarin, musk ambrette, sandalwood oil NSAIDs Oxicams: ampiroxicam, droxicam, meloxicam, piroxicam, tenoxicam Prioprionic acid derivatives: benzophenone, dexketoprofen, ketoprofen, piketoprofen, suprofen (UVA and UVB), tiaprofenic acid, diclofenac Antimicrobials: bithionol, chlorhexadine, fenticlor, hexachlorophene Phenothiazines: chlorpromazine, promethazine Miscellaneous Acyclovir Dibucaine Halogenated salicylanilides (UVA and UVB) Hydrocortisone