Bullous phytophotodermatitis associated with high natural concentrations of furanocoumarins in limes

Background: Phytophotodermatitis is a phototoxic reaction, occurring in skin exposed to sunlight after contact with plants containing furanocoumarins. Typical reactions are mild, showing erythema with postinflammatory hyperpigmentation. A 6-year-old boy presented with marked, symmetric, painful erythema and edema of both hands that rapidly developed into dramatic bullae covering the entire dorsum of the hands. The history revealed that the hands had been bathed in lime juice for a prolonged period in the preparation of limeade. Objective: This report documents an unusual bullous presentation of phytophotodermatitis resulting from contact with furanocoumarins in local limes. This study was conducted to identify and measure the inciting substances from the rind and pulp of the limes. Methods: Psoralen, xanthotoxin, bergapten, and isopimpinellin content were measured by gas chromatography and high-pressure liquid chromatography Results: The rind contained 6- to 182-fold concentrations of all furanocoumarins measured when compared with pulp. Bergapten was the most abundant substance in the rind. Conclusion: Hydration of the skin during the preparation of limeade combined with increased levels of bergapten in local limes to produce a dramatic bullous reaction. We encourage clinicians to consider the possibility of phytophotodermatitis in severe bullous skin reactions.