Picture Prognosis

A 29-year-old woman who recently emigrated from Ecuador presents with a chronic enlarging ulcer on the thigh that began as a pustule three months ago. The lesion has failed to respond to multiple courses of oral antibiotics. Skin biopsies show mixed dermal lymphoplasmacytic inflammation without identifiable organisms on routine stains or culture. Polymerase chain reaction (PCR) testing confirms Leishmania braziliensis. Which of the following is the most appropriate management?