A 50-year-old woman presented to the clinic with an intensely pruritic rash that had come on suddenly and extended over the dorsal aspect of both arms. She said that she had not begun taking any new medicines, and had no recent exposures to any new chemicals. She did, however, note that she’d recently spent some time in the sun.
Her history included schizoaffective disorder, bipolar disorder, reactive airways disease, type 2 diabetes mellitus, and hypertension.
She was taking a number of medications including trihexyphenidyl, flu- phenazine, mirtazapine, ibuprofen, propranolol, acetaminophen, albuterol/ipratropium inhaled, and triamcinolone inhaled. She reported being allergic to lithium, erythromycin, and haloperidol.
Her skin exam showed erythematous plaques over the dorsum of both forearms (Figure 1). There were no lesions on her left forearm where she had been wearing a watch, and there were no lesions on her face or lower extremities. Her vital signs were normal.
We ordered a punch biopsy.
FIGURE 1
Plaque on forearms, except under watchband
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