Phytophotodermatitis

The parents of an 8-year-old girl were concerned about an asymptomatic rash on their daughter’s hands. During the past 3 weeks, the rash had resolved and recurred.

The examination showed a child with Fitzpatrick skin type IV, who had a curious hyperpigmented, faintly scaly, and erythematous eruption confined to the dorsa of both hands; it seemed to originate from between the proximal interdigital areas. A potassium hydroxide examination was negative. The girl was otherwise healthy and had no other rashes.

Additional history taking revealed that the child often ate lemons and limes, carrying the dripping fruit around outdoors while she sucked on it. Her hands would often be soaked with the juice.

This is a classic clinical picture of phytophotodermatitis, a type of phototoxic reaction to photosensitizing chemicals present in a large number of plants, most notably lime, lemon, and oil of bergamot. In most cases, as with this patient, there is hyperpigmentation in an annular, guttate pattern formed by the liquid as it drips onto skin, followed immediately by sun exposure. Patients may also report mild irritation.

The darker the patient’s skin, the darker the hyperpigmentation, and the longer it takes for the condition to clear. No treatment is necessary.