Polymorphous Light Eruption

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Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Epidemiology 5 Pathology 6 Laboratory 7 Complications 8 Differential-diagnosis 9 Management 10 More General Terms 11 Additional Terms 12 References

More Specific Terms

• actinic prurigo

Introduction

• A group of heterogenous, idiopathic, acquired, acute & recurrent photodermatoses characterized by delayed skin reactions to UV radiation.

Etiology

• precipitated most frequently by exposure to UV-A, but also UV-B or by both
• since UV-A is transmitted through glass, PMLE may be preciptated while driving or riding in a motor vehicle
• appears to be a threshold for elicitation of PMLE
• may be delayed hypersensitivity reaction to antigen induced by UV radiation

Epidemiology

• average age of onset is 23 years
• most common of the photodermatoses
• all races
• much more common in females
• less frequently observed in sunbelt (year-round sun)
• often occurs for 1st time in individuals traveling for short vacations to the tropics in winter from northern latitudes
• occurs in spring & early summer in temperate zones

Pathology

• edema of the epidermis
• basal layer with spongiosis, vesicle formation & mild liquifaction degeneration
• no thickening or atrophy of the basement membrane
• dense lymphocytic ( T-cell) infiltrate in the dermis
• occasional neutrophils in the dermis
• edema of the papillary dermis
• endothelial swelling
• direct immunofluorescence for IgG is negative Clinical manifestions:
• monomorphous reaction consisting of macules, papules, plaques or vesicles ( papular & papulovesicular eruptions are most common)
• lesions are pink to red
• rash occurs suddenly after hours to days of sun exposure
• most frequently appears within 18-24 hours of exposure
• persists for 7-10 days
• areas of skin habitually exposed (face & neck) may be spared despite severe involvement of trunk & extremities
• pruritis & paresthesia may precede the rash
• chronic & recurrent disorder, may become worse each season
• patients may develop a tolerance by the end of summer, but generally recurs the following season
• spontaneous improvement or resolution generally occurs after several years

Laboratory

• serology: anti-nuclear antibody ( ANA) 3-19% [2]
• complete blood count ( CBC): no leukopenia
• biopsy (if plaque-type lesions)
• phototesting with UV-A & UV-B

Complications

• ANA+ PMLE does NOT transform to lupus [2]

Differential-diagnosis

• lupus erythematosus ( plaque-type lesions)
• drug reaction
• allergic reaction to cosmetic

Management

• sunscreens

• rarely effective, but should be tried 1st
• should be used in conjunction with systemic medication or PUVA

• beta carotene not very effective, but may be tried
• hydroxychloroquine 200 mg PO BID

• one day before & daily while vacationing or on weekends in the sun
• effective in some patients
• use in patients not helped by sunscreens or beta-carotene

• PUVA photochemotherapy

• given in early spring induces tolerance for the following summer
• treatments 3 times weekly for 4 weeks
• repeat each spring for 3-4 years

More General Terms

• skin disease (dermatologic disorder, dermatopathy, dermatosis)

Additional Terms

• beta-carotene
• hydroxychloroquine (Plaquenil)
• oral psoralen & ultraviolet (UV) A light (PUVA)
• paresthesia
• pruritis (itching)
• UV-A radiation
• UV-B radiation

References

1. Color Atlas & Synopsis of Clinical Dermatology, Common & Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 250-53
2. Tzaneva S et al Antinuclear antibodies in patients with polymorphic light eruption: a long-term follow-up study. Br J Dermatol. 2008 May;158(5):1050-4. Epub 2008 Mar 13. PMID: [1]

polymorphous light eruption (PMLE)