Polymorphous light eruption in Adult
PMLE is most commonly seen in women with lighter skin phototypes aged 20-30, but it can occur in either sex, all ages, and all ethnicities. Attacks most commonly occur during the spring and early summer months, especially after the first sun exposure of the season, and disappear during the winter.
The etiology of PMLE is not well understood. One theory is that UVR modifies antigens in the skin of PMLE patients to make them immunogenic. There are also data to suggest that PMLE involves a type IV delayed-type hypersensitivity reaction. The action spectrum for PMLE is UVA in most cases, but UVB and both UVA and UVB may also incite the response.
Although the condition frequently recurs, the tendency toward the development of PMLE and the severity of the eruption diminish with repeated sunlight exposure. This phenomenon is termed "hardening." As the summer proceeds, it has been observed that the incidence of new eruptions decreases. Prophylactic phototherapy supports this concept of hardening or tolerance.
Despite the variability of presentations, individual patients tend to experience the same clinical manifestations with each episode.
L56.4 – Polymorphous light eruption
238525001 – Polymorphic light eruption
- Systemic lupus erythematosus – Check for circulating antinuclear antibodies (ANA) and other associated lupus antibodies; direct immunofluorescence will be positive; skin lesions can be located on sun-exposed and sun-protected areas (in contrast to PMLE, which is primarily in sun-exposed sites).
- Solar urticaria – Shorter time to onset of eruption with urticarial plaques lasting 1-2 hours.
- Erythema multiforme – Characteristic target lesions; systemic symptoms are prominent (in contrast to PMLE, where fever, malaise, nausea, and headache are rare).
- Hydroa vacciniforme
- Porphyria cutanea tarda – Will have abnormal porphyrin profile (elevated urine uroporphyrin and stool isocoproporphyrin).
- Erythropoietic protoporphyria – Lesions are very painful, and there is an elevated red blood cell protoporphyrin concentration.
- Photoallergic drug reaction – Investigate for drug history; not seasonally associated and does not improve over time.
- Phototoxic drug reaction
- Airborne contact dermatitis
- Drug-induced pseudoporphyria