Caitlin,
I'm hoping my colleagues will join in on this discussion. I'm not quite sure what arterial studies were done . I have to assume that they were looking at macro vascular disease and have not looked for microvascular issues... Secondly, my thought here is the patient needs a biopsy and cultures to be done. Not knowing much more about the patient's history this could be an atypical ulcer. Laboratory studies can also be helpful in ruling and ruling out certain entities. Certain medications such as hydroxyurea also can contribute to the formation of leg ulcers. I can't stress enough about doing a deep dive into the patient's history.This can be extremely important - especially in this case. This does not appear to be a wound that can be treated topically.