What is polymorphous light eruption (PMLE)?
Polymorphous light eruption (PMLE), a common skin condition in the form of a rash, is generally triggered by exposure to ultraviolet (UV) light. Sometimes it is called polymorphic light eruption. “Polymorphous” means it looks different in different individuals.
PMLE shows on parts of the body exposed to UV light, including the arms, hands, chest, legs and feet. It is a benign (not cancerous) condition that resolves without scarring.
Who is likely to have polymorphous light eruption (PMLE)?
While anyone can develop PMLE, the condition is most common in people under age 40. It most often happens in the spring and summer in residents of a temperate climate. Or it can occur when there is an abrupt increase in one’s level of sun exposure, such as on a sunny vacation.
Is polymorphous light eruption (PMLE) contagious?
Polymorphous light eruption is not contagious (does not spread to others).
Symptoms and Causes
What causes polymorphous light eruption (PMLE)?
No one knows exactly what causes polymorphous light eruption. It is thought that a compound in the skin is altered by UV radiation and that the immune system reacts to the new compound.
What are the symptoms of polymorphous light eruption (PMLE)?
Polymorphous light eruption typically presents as an itchy rash on the arms, hands, chest, legs and feet. The face is less commonly affected. The rash may consist of small red bumps, larger red patches or even blisters.
In rare cases, PMLE causes symptoms such as:
Most people develop symptoms within several hours of UV light exposure, either from the sun or an artificial source such as a tanning bed.
In general, symptoms of PMLE last for two to three days. Repeated UV light exposure while the rash is present may cause it to last longer.
Diagnosis and Tests
How is polymorphous light eruption (PMLE) diagnosed?
Polymorphous light eruption is typically diagnosed with a thorough history and skin examination. A skin biopsy, or tissue sample, may be obtained to confirm the diagnosis.
Your doctor may recommend a blood test to rule out other medical conditions such as lupus erythematosus, an autoimmune disease that can also cause a facial rash.
Management and Treatment
How is polymorphous light eruption (PMLE) treated?
In some cases, PMLE resolves on its own with no treatment. However, more severe cases may require medications such as:
People living with PMLE should avoid exposure to sunlight, especially between 11 a.m. and 3 p.m., when UV rays are strongest. Using high SPF, broad-spectrum sunscreen and wearing protective clothing helps minimize UV light exposure.
Some patients benefit from phototherapy as a way to “harden” the skin. Repeated, controlled exposure to natural or artificial UV light helps desensitize skin and prevents future rashes.
Outlook / Prognosis
What is the prognosis (outlook) for people with polymorphous light eruption (PMLE)?
For most people with polymorphous light eruption, symptoms improve or resolve over years, but the condition may be life long.
Polymorphous light eruption is benign, but rarely, patients go on to develop lupus erythematosus.
When should I call my doctor?
If you develop a rash shortly after exposure to sunlight or artificial UV light, ask your doctor if you could have polymorphous light eruption.
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