METHODS: Combined bone scanning and immunoscintigraphy (IS) with 99mTc-monoclonal antigranulocyte antibodies were performed in two patients with suspected reactivation of chronic osteomyelitis of the lower extremity. Because bone scanning and IS were strongly positive, both patients underwent surgical intervention. RESULTS: Macroscopic findings did not show purulent infection and microbiologic results remained negative, but histology revealed unexpected ectopic bone marrow, explaining the strong uptake on IS. One patient exhibited active hematopoietic bone marrow at the former fracture site of the tibial bone. The second patient presented with interspersed bone marrow in the cortical bone of the femoral diaphysis after several intramedullary surgical procedures. CONCLUSION: Unexpected ectopic hematopoietic marrow may occur in the appendicular skeleton after trauma and repeated surgical interventions. The bone marrow shows a physiologic uptake with IS and may be misinterpreted as granulocyte accumulation due to infection. This may lead to false-positive diagnosis in cases of suspected osteomyelitis.
METHODS: Combined bone scanning and immunoscintigraphy (IS) with 99mTc-monoclonal antigranulocyte antibodies were performed in two patients with suspected reactivation of chronic osteomyelitis of the lower extremity. Because bone scanning and IS were strongly positive, both patients underwent surgical intervention. RESULTS: Macroscopic findings did not show purulent infection and microbiologic results remained negative, but histology revealed unexpected ectopic bone marrow, explaining the strong uptake on IS. One patient exhibited active hematopoietic bone marrow at the former fracture site of the tibial bone. The second patient presented with interspersed bone marrow in the cortical bone of the femoral diaphysis after several intramedullary surgical procedures. CONCLUSION: Unexpected ectopic hematopoietic marrow may occur in the appendicular skeleton after trauma and repeated surgical interventions. The bone marrow shows a physiologic uptake with IS and may be misinterpreted as granulocyte accumulation due to infection. This may lead to false-positive diagnosis in cases of suspected osteomyelitis.