A 38-year-old man from Mumbai presents with a 3-month history of violaceous, flat-topped papules on the dorsal surfaces of both hands and wrists, with a fine reticular pattern visible on close inspection. The lesions are mildly pruritic. Dermoscopy shows the characteristic Wickham's striae. Oral examination is unremarkable. Skin biopsy confirms lichen planus. Liver function tests and hepatitis C serology are negative. What is the most appropriate next step in management?