High-Intensity Focused Ultrasound Therapy for an Osteoidosteoma in a Pediatric Finger: A Case Report

Background High intensity focused ultrasound (HIFU) is a non-ionizing and non-invasive application for benign and malign disease. Ultrasonic waves are concentrated to achieve high level of energy and therefore necrosis due to coagulation. Aims We will describe one pediatric case where an osteoidosteoma war successfully treated by HIFU. Methods A seven-year-old boy presented in our department for hand surgery due to indolent swelling of the distal phalanx of the right ring finger. Neither recent trauma, nor positive family history was present. Clinical examination showed significant enlargement of the distal phalanx with minimal pain on palpation and unlimited mobility. Conventional radiography showed discrete fuzzy sclerosis of the metaphyseal part of the growth plate. MRI was not conclusive. Bone biopsy showed reactive change with no signs for acute inflammatory event. Periodic checks were performed, with no change in clinical and radiographic aspect. Nine months after the first appointment, the patient presented with pain after minor trauma and increase of the swelling. Radiography showed a nidus in the distal phalanx leading to a suspected diagnosis of an osteoidosteoma. Therefore, MRI-guided HIFU (MR-HIFU) was recommended one year after the first appointment. Results MR-HIFU was performed to destroy the osteoidosteoma. Six months after the intervention the patient presented with no further exponential growth and the difference to the other phalanges was minimized. Furthermore, radiography showed no retention of the nidus with a plane distal phalanx. Conclusion MR-HIFU is a promising approach in the non-invasive treatment of tumorous neoplasm. Because of its non-ionizing ultrasonic waves, there is no upper limit in dosing. The deposition of heat is in general limited by the surrounding tissue. The main factors preventing MR-HIFU treatment are thick bone around the nidus, a superficial position with risk for skin burn and the vicinity to neural structures. Osteoidosteomas are generally rather small and therefore well suited for MR-HIFU.