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Differential Diagnosis
- Arthropod bites
- Excoriated eczema
- Actinic prurigo
- Polymorphous light eruption
- Prurigo nodularis
- Seborrheic dermatitis
- Solar urticaria
Diagnosis
The correct diagnosis is actinic prurigo (AP), also called Hutchinson’s summer prurigo, which is a rare, photoinduced skin eruption triggered by exposure to ultraviolet (UV) radiation. AP is a delayed-type hypersensitivity reaction, although its precise pathogenesis remains unclear. Both UVA and UVB radiation have been implicated in triggering symptoms. AP is most frequently seen in indigenous populations of North, Central, and South America and usually first presents during childhood. It is more common in females, although studies from Asia report a male predominance in adult-onset disease.
The diagnosis of actinic prurigo is often based on history and clinical findings. Up to 50% of patients report a family history of similar eruptions. Additional evaluation may include biopsy, phototesting and laboratory testing including serum immunoglobulin E (IgE), which is nearly always elevated in moderate to severe cases.
What to Look For
- The hallmark symptoms of actinic prurigo are symmetrically distributed excoriated, pruriginous papules and nodules in photo-exposed areas(especially the face) which are intensely pruritic. Hemorrhagic crusts, eczematous patches, lichenification and/or scarring may also be present.
- Many patients also experience perioral tingling and pain, conjunctivitis, photophobia, and increased lacrimation.
- The onset of actinic prurigo typically occurs in the spring, when more time is spent outdoors and more skin is exposed; the lesions can persist through the summer.
- actinic prurigo may have a protracted course that extends into the winter months. Patients with childhood onset may spontaneously improve in adolescence, but the condition can persist into adulthood, with a major impact on the patient’s quality of life.
Pearls For Urgent Care Management
- Sun-avoidance and sun-protective practices, including broad-spectrum sunscreens and protective clothing, are the mainstay of the management of actinic prurigo.
- Mild to moderate disease: Topical corticosteroids and topical calcineurin inhibitors can offer symptomatic relief in mild cases.
- Severe disease: Patients with severe actinic prurigo require treatment with systemic immunomodulators, immunosuppressants or phototherapy, and should be referred to primary care or dermatology specialists.
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