A non-healing ulcer may be due to an underlying skin cancer like basal cell carcinoma.
The 1st thing to do is to see your dermatologist to get it checked out. A skin biopsy can be done to confirm the if this is indeed due to a pigmented basal cell carcinoma.
Once confirmed, surgical excision is the main treatment option. Mohs surgery is a form of surgery and this is indicated when 'tissue preservation' is important to minimize the size of the excison. Moh's surgery is performed by a dermatologist who specializes in the procedure.
