A 40-year-old man presented to an American allergy clinic with a burning sensation and irritation on both hands for two days. The day before, he had squeezed the juice from 12 limes with his hands and then attended an outdoor soccer game without using sunscreen. Upon examination, he observed confluent erythema extending from the dorsal surfaces of his thumbs to the medial surfaces of his index fingers on both sides, with scattered areas of erythema on his knuckles and other fingers. There was no erythema under the ring finger; a small blister was present at the base of his left thumb. Drs. Vishaka Ravishankar Hatcher of Joint Base San Antonio and Charles Kent Miller of Nellis Air Force Base Medical Center shared this case in the New England Journal of Medicine.
Based on the patient's medical history and examination data, he was diagnosed with phytophotodermatitis. This is a phototoxic, non-immunological skin reaction caused by exposure to furocoumarins—photosensitizing compounds found in lime, celery, parsley, hogweed, and other plants—and ultraviolet light. The man was prescribed a cream containing the glucocorticoid triamcinolone and emollients. Four days after exposure to the juice, another blister appeared on his right thumb. Two weeks later, hyperpigmentation and flaking developed, but the skin returned to normal within a few months.
