actinic prurigo; hydroa estivale; Hutchinson's summer prurigo

Introduction

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

• dermatosis generally disseminated, bilateral, & symmetric
• affects sun-exposed areas
• papules, plaques & nodules mostly on the face
• lesions appear hours or days following sun exposure
• lesions have serosanguineous crusting
• because the disorder is chronic, lichenification eventually occurs
• may cause disfigurement
• 65% of patients have cheilitis
• 45% of patients have bilateral conjunctivitis

* images

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

More general terms

• polymorphous light eruption (PMLE)
• genetic disease of the skin (genodermatosis)
• prurigo