phytophotodermatitis

Phytophotodermatitis is a phototoxic skin reaction that occurs after contact with certain plants containing furocoumarins (psoralens) followed by exposure to ultraviolet A (UV-A) radiation. Common source plants and substances include citrus fruits such as lemons and limes, celery, parsley, fig, and bergamot oil used in perfumes and cosmetics. The reaction can occur when juice, sap, or leaf contact is followed by sun exposure.

Mechanism and clinical features: Furocoumarins absorb UVA and cause DNA damage in skin cells, producing reactive oxygen species. Clinically, it presents with erythema, edema and sometimes vesicles or bullae within hours of exposure. The distribution is often linear or streak-like on sun-exposed areas where plant juice ran or where the skin was touched, commonly the hands, forearms, and face. Hyperpigmented patches may persist for weeks to months.

Diagnosis and management: Diagnosis is clinical, based on history and appearance; phototesting or patch testing is rarely needed. Management includes immediate washing of skin, avoidance of plant contact, and sun protection. Symptomatic treatment with cool compresses, topical corticosteroids for inflammation, analgesics for pain, and appropriate wound care for blisters. Hyperpigmentation can take months to fade. Severe or extensive cases may require systemic corticosteroids.

Prevention and prognosis: Prevention involves protective clothing and gloves when handling known phototoxic plants and prompt washing of exposed skin; avoid sun exposure during healing. Prognosis is typically good with resolution of acute lesions and gradual fading of hyperpigmentation; scarring is uncommon.