Lime-Induced Phytophotodermatitis

A 31-year-old man presented after 1 week of painless rash on his left hand. Examination revealed three non-blanching hyperpigmented macules with mild scaling (Fig. 1). Based on patient history of mixing margaritas outdoors 2 days prior to rash onset, he was diagnosed with phytophotodermatitis. Phytophotodermatitis is a common non-immunologic cutaneous reaction caused by topical exposure to furocoumarin compounds in the presence of sunlight. Furocoumarins in limes, carrots, celery, dill, fennel, figs, parsley, and parsnips sensitize epithelial DNA to ultraviolet light.¹ Cutaneous reactions are limited to contact areas and are often delayed by 36–72 h. Diagnosis is challenging because of the ubiquity of photosensitizing agents and the delayed onset. Involvement of skin in direct contact with beverage glasses is common, as are “drip lines” and even secondary hand imprints, which have been misdiagnosed as child abuse.² Asymptomatic hyperpigmentation is the most common reaction, but exposure can lead to severe sunburn with blistering, which may require treatment in burn units.³ Treatment is symptomatic, with rash resolution in weeks, though hyperpigmentation can persist for months. Avoidance of topical furocoumarins and protection of skin from over-exposure to sunlight are preventive.

Figure 1.

Clinical image showing hyperpigmented macules with mild scaling over patient’s left hand.