An 18-year-old girl comes to the emergency department due to a painful rash. She had just spent an hour at the beach when she began to experience a burning sensation, followed by sudden onset of redness and swelling in sun-exposed areas. The patient sees a dermatologist for facial acne and was recently started on a new treatment. Temperature is 37.2 C (99 F), blood pressure is 108/68 mm Hg, pulse is 82/min, and respirations are 14/min. Skin examination is notable for erythema, edema, and vesicles at the face, anterior neck, upper chest, and dorsal surface of the hands and forearms. There are no mucosal lesions. Which of the following best explains the patient's current condition?

Question

An 18-year-old girl comes to the emergency department due to a painful rash.  She had just spent an hour at the beach when she began to experience a burning sensation, followed by sudden onset of redness and swelling in sun-exposed areas.  The patient sees a dermatologist for facial acne and was recently started on a new treatment.  Temperature is 37.2 C (99 F), blood pressure is 108/68 mm Hg, pulse is 82/min, and respirations are 14/min.  Skin examination is notable for erythema, edema, and vesicles at the face, anterior neck, upper chest, and dorsal surface of the hands and forearms.  There are no mucosal lesions.  Which of the following best explains the patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d371_cbe5_bc81_8550a1265377_MD0003_00 This patient is experiencing a systemic phototoxic drug reaction to her acne medication. Phototoxic drug reactions result from the production of reactive oxygen species by the interaction of drug metabolites with ultraviolet radiation. These reactive oxygen products then directly damage cell membranes and DNA. Symptoms resemble common sunburn, with erythema, pain, and bullae formation in sun-exposed areas. However, the reactions may have exaggerated severity, and the solar exposure needed to cause symptoms may be much less than that needed to cause nonphototoxic sunburn. Tetracyclines (eg, doxycycline) are frequently prescribed in the treatment of acne and are a very common cause of phototoxic drug reactions. Patients being prescribed tetracyclines should be advised to minimize sun exposure and use appropriate sunscreens and barrier solar protection when outdoors. Topical (eg, sunscreens) and systemic medications can also cause photoallergic reactions, in which ultraviolet light alters the structure of the drug, which then induces a delayed hypersensitivity reaction. These skin manifestations are typically eczematous in appearance. Prior sensitization is required for a photoallergic response, but not a phototoxic reaction. (Choice A) Allergic contact dermatitis can occur with most topical medications and causes erythema, itching, and vesicle formation. Contact dermatitis is less likely in this patient as it would be unlikely to cause such acute symptoms and would not typically affect areas (eg, neck, chest) where the medication was not applied. (Choice B) Benzoyl peroxide can cause photosensitivity, but less commonly than the tetracyclines, and would not involve untreated areas. Common side effects of benzoyl peroxide include irritation, contact dermatitis, dryness, erythema, peeling, and stinging. (Choice D) Erythromycin can cause gastrointestinal upset and cholestatic jaundice (estolate base), but it is not a common cause of photosensitivity. (Choice E) Stevens-Johnson syndrome is a severe mucocutaneous reaction most commonly triggered by medications (eg, sulfa drugs, anticonvulsants). Affected patients develop acute high fever, vesicular or bullous lesions, and painful hemorrhagic oral erosions. lesions Educational objective: Tetracyclines are an important cause of phototoxic drug eruptions. These eruptions manifest as exaggerated sunburn reactions with erythema, edema, and vesicles in sun-exposed areas. References: Effect of tetracycline and UV radiation on melanization and antioxidant status of melanocytes. (http://www.ncbi.nlm.nih.gov/pubmed/25935746)

An 18-Year-Old Girl Comes to the Emergency Department Due to a Painful