Dermatofibrosarcoma protuberans

My 10-year-old son was diagnosed with DFSP (Dermatofibrosarcoma Protuberans) last year. Since then, he has undergone three surgeries here in Canada, but unfortunately, none have been successful due to inconsistent treatment approaches. We are desperately looking for the right hospital or medical team with expertise in treating DFSP in children. If anyone has experience or can recommend a trusted hospital or specialist, we would be incredibly grateful for your help.