Further treatment might be required if bullous lesions are present. Small blisters can be punctured and drained; however, large blisters, extensive epidermal-dermal separation, and large areas of detached epidermis should simply be cleansed and dressed. An oral steroid also can be used to reduce inflammation in moderate and severe cases. Full-thickness injury might require surgical intervention.8
Clinical Case
A 27-year-old male landscaper presented to the emergency department with an increasingly painful blistering rash on the arms and neck of 1 day’s duration. He noticed bright red skin and blisters 18 to 24 hours after trimming what he identified as shoulder-high giant hogweed plants. Neither he nor his coworkers were wearing sunscreen or protective clothing as they cleared the plants for several hours. His coworkers developed similar rashes, but his rash was the most severe, requiring treatment in the emergency department.
Physical examination showed innumerable 2- to 10-mm, tense vesicles and bullae on a background of blanching erythema in a striking photodistribution along the neck (Figure 2) and arms (Figure 3). He had notable edema of both arms and several large 3- to 4-cm bullae on the ventral aspects of the forearms.
FIGURE 2. Bullae and erythema on the sun-exposed region of the posterior neck due to giant hogweed phytophotodermatitis.
The patient was diagnosed with severe phytophotodermatitis secondary to contact with H mantegazzianum and was started on oral prednisone 70 mg daily (1 mg/kg/d), which was decreased by 10 mg every 3 days until the course of treatment was complete. He also was instructed to apply mupirocin ointment to open areas and petroleum jelly to intact skin. Additionally, he was advised to practice strict photoprotection for the near and distant future.
FIGURE 3. Vesicles and bullae on the sun-exposed region of the right arm due to giant hogweed phytophotodermatitis.
Within several days after treatment began, the phytophotodermatitis dramatically improved, with complete resolution in 1 week. Postinflammatory hyperpigmentation resolved after several weeks.