Image 3. A young man traveled down across the Sahara desert and then east to Ethiopia. On his return to Canada he had a nontender 1 cm healing-furuncle like lesion on the lateral aspect of his calf. He was afebrile The lesion gradually enlarged to 20 cm over 4 months. It was stiff but not painful and there was no fever. Early biopsies revealed no etiology. The diagnosis is
