What disease, known in antiquity but largely eradicated from the developed world, caused this severe facial scarring?
An undernourished child presents with a facial lesion present for some months (Figure). The problem started as a gingival ulcer with facial edema and progressed to a necrotic black escar. After sloughing of the escar and the external cheek skin, the area finally healed with a scar and retraction over the course of the next weeks.
What is the most likely diagnosis?