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actinic prurigo; hydroa estivale; Hutchinson's summer prurigo
Hereditary form of polymorphous light eruption in Native Americans.
Etiology:
- abnormal reaction to sunlight
- UV-A & UV-B light seem to be the main provoking agents
Epidemiology:
- Native Americans
- 1/3 of cases in children
- most patients present in spring or summer
- symptoms may persist into fall & winter, especially in tropical areas
- most patients live at high altitudes (>1000 m above sea level)
- the condition improves in many patients when they move to lower altitudes
Pathology:
- acanthosis, mild spongiosis, edema of the lamina propria
- moderate-to-dense bandlike lymphocytic infiltrate
- occasionally, lymphoid follicles
- vacuolization of the basal cell layer & dilated capillaries in the dermis
- affected conjunctivae show epithelial hyperplasia alternating with atrophy
Clinical manifestations:
1) dermatosis generally disseminated, bilateral, & symmetric
2) affects sun-exposed areas
3) papules, plaques & nodules mostly on the face
4) lesions appear hours or days following sun exposure
5) lesions have serosanguineous crusting
6) because the disorder is chronic, lichenification eventually occurs
7) may cause disfigurement
8) 65% of patients have cheilitis
9) 45% of patients have bilateral conjunctivitis
* images [2,3]
Laboratory:
- as needed to rule out systemic diseases with photosensitivity
- antinuclear antibody (systemic lupus erythematosus)
- anti-SSA/Ro antibody negative
- anti-SSB/La antibody negative
- poryphyrins in urine negative (porphyria)
Management:
- avoid sunlight, use protective clothing
- thalidomide 100 mg QD, gradually taper
- teratogenic: women in their childbearing years must use contraceptives
- topical glucocorticoids
- conjunctivitis may respond to 2% cyclosporine A ophthalmic
- once lesions remit, use sunscreens
General
polymorphous light eruption (PMLE)
genetic disease of the skin (genodermatosis)
prurigo
References
- Color Atlas & Synopsis of Clinical Dermatology, Common
& Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY,
1997, pg 250
- Castanedo-Cazares JP, Elston DM (images)
Medscape: Actinic Prurigo
http://emedicine.medscape.com/article/1120153-overview
- DermNet NZ. Actinic prurigo (images)
http://www.dermnetnz.org/reactions/actinic-prurigo.html