Florid reactive periostitis.

Florid reactive periostitis (FRP) is a benign entity, mostly involving the tubular bones of the hands and feet. It is important to distinguish FRP from malignant processes such as periosteal osteosarcoma and parosteal osteosarcoma, to give an adequate treatment and to avoid amputation of the total digit. The final diagnosis of FRP is usually based on the combination of clinical, radiological, and pathological findings. The pattern seen on the isotope bone scan can be very helpful in orienting the differential diagnosis.