A 36-year-old man comes to the urgent care center due to a 2-day history of a pruritic rash on his hands. It began with small papules and progressed to small blisters with oozing yellow fluid. A few days prior, the patient spent an afternoon clearing bushes around his house but has had no recent travel or change in household products. Medical history is unremarkable. Temperature is 36.6 C (97.9 F), blood pressure is 125/79 mm Hg, and pulse is 76/min. Skin examination shows erythematous plaques with eroded vesicles and small bullae between the fingers of the left hand and on the dorsum of the right hand, as shown in the exhibit. Which of the following is the most likely diagnosis for this patient?
Allergic contact dermatitis | |
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This patient with pruritic erythematous plaques, vesicles, and bullae that developed a few days after contact with plants most likely has acute allergic contact dermatitis (ACD) due to Toxicodendron species (poison ivy/oak/sumac). ACD is a type IV hypersensitivity reaction that can be triggered by a variety of allergens, including plants, natural rubber, leather dyes, nickel, topical medications, and skin care products.
Toxicodendron produces urushiol, a highly allergenic resin. In sensitized individuals, the rash can develop within 4-96 hours of exposure; in previously unexposed individuals, it may not be seen for 3 weeks. The typical rash, as seen in this patient, is usually limited to exposed skin, frequently forming linear streaks where skin has brushed against plant leaves. However, diffuse or atypical patterns can be seen after exposure to contaminated clothes, pets, or smoke from burning plants. Treatment typically involves high-potency topical or oral corticosteroids.
(Choice A) Bullous impetigo, a skin infection caused by Staphylococcus aureus, presents with rapidly enlarging vesicles and bullae, which rupture to yield exudates and crusts. Pruritus can be present, but the surrounding skin usually has little to no erythema. The condition is most common in children; occurrence in an adult is unusual unless the patient is immunocompromised (eg, HIV infection).
(Choice B) Bullous pemphigoid is a chronic (not acute), pruritic, autoimmune, blistering disease that typically affects people age >60. Areas affected include axillae, medial thighs, groin, abdomen, forearms, and lower legs. Isolated involvement of the digits and hands is atypical.
(Choice D) Herpetic whitlow is an acute herpes simplex virus infection of the hand, often occurring in patients with concurrent herpes labialis. It begins as tingling and pain, with the progressive appearance of small, clustered vesicles on an erythematous base. It most commonly affects a single digit; bilateral involvement is rare.
(Choice E) Sporotrichosis is typically acquired by direct inoculation of the skin by a plant (eg, rose thorn) containing the fungus. It presents with ulcerating, pustular nodules at the site of inoculation (eg, usually on 1 hand) and associated lymphatic channels. The lesions are generally asymptomatic; vesicles and bullae are not characteristic.
Educational objective:
Toxicodendron plants (poison ivy/oak/sumac) are a frequent cause of allergic contact dermatitis. The intensely pruritic, erythematous, vesicular rash involves exposed skin, forming linear streaks where skin has brushed against the plant leaves. However, diffuse or atypical patterns can be seen after exposure to contaminated clothes, pets, or smoke from burning plants.