Polymorphic Light Eruption (PMLE)

Polymorphic light eruption (PMLE) is a common skin condition characterized by an abnormal sensitivity to sunlight, particularly ultraviolet (UV) radiation. It is also known as polymorphic light eruption or sun poisoning.

Causes and Triggers

The exact cause of PMLE is not fully understood, but it is believed to be related to an immune system reaction to UV radiation. Certain factors can trigger the condition, including:

• Exposure to sunlight, especially during peak hours (10am-4pm)
• Reflection of sunlight off water or sand
• Cloud cover, which can scatter UV radiation and increase exposure
• Hormonal changes, such as those experienced during pregnancy or menstruation
• Certain medications, including antibiotics and antihistamines

Symptoms

The symptoms of PMLE can vary in severity and appearance, but common characteristics include:

• Red, itchy, and inflamed skin lesions or rashes
• Blisters or bumps on the skin
• Papules (small, raised bumps) or plaques (larger, flat areas of inflammation)
• Skin discoloration, such as hyperpigmentation (darkening of the skin) or hypopigmentation (lightening of the skin)

Diagnosis

Diagnosing PMLE typically involves a physical examination and medical history. A healthcare provider may also perform:

• A skin biopsy to rule out other conditions, such as lupus or eczema
• Phototesting, which involves exposing the skin to different wavelengths of light to determine sensitivity
• Patch testing to identify potential allergens or irritants

Treatment and Prevention

Treatment for PMLE typically focuses on relieving symptoms and preventing future episodes. Common approaches include:

• Topical corticosteroids to reduce inflammation and itching
• Oral antihistamines or anti-itch medications to relieve itching and discomfort
• Photoprotective measures, such as wearing protective clothing, seeking shade, and using broad-spectrum sunscreen with a Sun Protection Factor (SPF) of at least 30
• Avoiding peak sun hours and reflective surfaces

Complications and Prognosis

If left untreated or poorly managed, PMLE can lead to complications such as:

• Post-inflammatory hyperpigmentation (PIH), which can result in long-term skin discoloration
• Skin scarring or textural changes
• Emotional distress and decreased quality of life due to discomfort and self-consciousness about appearance

The prognosis for PMLE is generally good, with most people experiencing improvement in symptoms with proper treatment and prevention. However, some individuals may experience recurring episodes or persistent symptoms.