PURPOSE OF THE STUDY Osteoid osteoma is a benign tumor that forms in bone, which accounts for 3% of all primary bone tumors. The classical clinical finding is substantial nocturnal pain and imaging findings. The management of osteoid osteomas include open surgical excision or minimally invasive percutaneous interventions. Why and which treatment modality should be considered between CT-guided radiofrequency ablation and open surgical excision for osteoid osteomas in unusual locations? MATERIAL AND METHODS We retrospectively reviewed 17 patients with osteoid osteomas in unusual locations included cuboid, triquetrum, coronoid process, and proximal phalanx. We evaluated the duration from symptoms to diagnosis, activity related pain, clinical findings, and possible recurrence or complications. The minimum clinical follow-up was 51 ± 34.8 months. RESULTS CT-guided radiofrequency ablation was applied to 3 patients and open surgical excision procedures to 14. All the complaints of patients gone after treatment. No major complications were observed following CT-guided radiofrequency ablation or surgical excision. Transient weakness/paresthesia was determined in 1 patient in the treated shoulder after CT-guided radiofrequency ablation, which resolved spontaneously in the 6th week. There was only recurrence seen in 1 patient, who had 2nd proximal phalangeal osteoid osteoma. Proximal interphalangeal joint arthrodesis was performed after recurred lesion. DISCUSSION The main challenge in management of the osteoid osteomas of the unusual locations are the diagnosis. When we examined the literature, the interval from the beginning of the symptoms to accurate diagnosis did not change over the past decades. Techniques for management of these lesions should be chosen with consideration of the location of the lesion. CONCLUSIONS If there is long-term complaint of undiagnosed limb pain, the physician should suspect osteoid osteoma. However, the selection of treatment modality should be considered according to the location of the lesion. Which management modality is superior may change depending on the location of the lesion between CT-guided radiofrequency ablation and surgical excision. Key words: osteoid osteoma, unusual locations, CT guided, radiofrequency ablation, benign bone tumor.

University of Health Sciences Diskapi Yildmm Beyazit Research and Training Hospital Department of Orthopaedics and Traumatology Ankara Turkey

University of Health Sciences Kartal Dr Lütfi Kirdar Research and Training Hospital Department of Pathology istanbul Turkey

University of Health Sciences Kartal Dr Lütfi Kırdar Research and Training Hospital Department of Orthopaedics and Traumatology İstanbul Turkey

Management of Osteoid Osteoma in Unusual Locations