Hi. Your description of a deep non-healing ulcer is suggestive of a Vasculitis, though a biopsy from the edge of the ulcer would be the ideal test to confirm the same. Vasculitis in the lower limb may be due to many reasons, including infection (like tuberculosis, leprosy), primary cutaneous vasculitis (cutaneous polyarteritis) or as part of a primary systemic vasculitis(with other organ manifestations). Management would be decided based on the type of vasculitis and the etiology. Please consult a Rheumatologist, who is well versed with the different causes of vasculitis and their management for the same. Thank you.