A 58-year-old woman presents with a pruritic, violaceous, flat-topped papule on her flexor wrist for 3 months. Biopsy shows a band-like lymphocytic infiltrate at the dermoepidermal junction with sawtooth rete ridges and Civatte bodies. She recently started hydrochlorothiazide 6 months ago. Which finding would most strongly support a lichenoid drug reaction over idiopathic lichen planus?

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