This is an interesting one,
It is not conventional plantar fasciitis,
I Don’t think it is plantar fibromatosis either.
Given the patients age I think a focal nodular fasciosis would also be unlikely.
With the history of martial arts trauma I think it must be an acute injury.
I would go for a partial tear of the fascia and associated healing / fibrosis. This would explain the small cystic area and also the vascularity.
I often wonder if patients with standard type plantar fasciitis begin this way. Often I can see a small linear split in the fascia and there is an enthesis defect at the calcaneum. When you take a clinical history the patient recalls an acute event which has been the catalyst for the plantar fasciitis.
Nice case.
Steve