title: Osteoid osteoma of the acetabulum successfully treated with computed tomography-guided resection and ablation using a standard electrosurgical generator: a case report.
abstract: BACKGROUND
  Osteoid osteoma accounts for approximately 10% of all benign bone tumors. The most common sites of osteoid osteoma are the subcortical shaft and metaphyses of long bones, but any other skeletal bone site can be involved. The acetabulum is a rare site according to past reports. This site presents challenges to optimal management because it is anatomically difficult to approach, and because its rarity leads to limited experience with therapeutic procedures. Here, we report for the first time a rare case of osteoid osteoma in the acetabulum that was successfully treated via resection of the nidus and ablation using a standard electrosurgical generator under computed tomographic guidance.
  
  
  METHODS
  A 9-year-old Japanese girl presented at a clinic with left hip pain without apparent cause for 1 month. She was diagnosed as having coxitis simplex. However, her pain did not change for 1 year and she was admitted to another hospital where osteoid osteoma in her left acetabulum was suspected. She was then referred to our hospital approximately 1 year after first symptom presentation, where she presented with severe left hip pain and was completely unable to walk. Computed tomography examinations revealed a well-demarcated 5 mm mass with bone sclerosis in her left acetabulum. The mass was characterized by low intensity on T1 and high intensity on T2 magnetic resonance images. These findings were consistent with osteoid osteoma of left acetabulum. She underwent computed tomography-guided resection of nidus and ablation using a standard electrosurgical generator. A histological examination confirmed acetabular osteoid osteoma. Complete pain relief was achieved after the procedure and she experienced no complications. She could walk without any pain at the final follow-up 1 year post-treatment and no local recurrence was observed.
  
  
  CONCLUSIONS
  We successfully treated acetabulum osteoid osteoma without any symptom recurrence by computed tomography-guided resection and ablation using a standard electrosurgical generator. In addition, we preserved our patient's sciatic nerve and triradiate cartilage. Our report provides evidence that a computed tomography-guided procedure should be considered the treatment of choice for osteoid osteoma of the acetabulum because it is a less invasive alternative to en bloc resection.
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan. kkikuta922@gmail.com.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kikuta
authors.affiliation: Department of Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Sota
authors.initials: S
authors.lastname: Oguro
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sekita
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Michiro
authors.initials: M
authors.lastname: Susa
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Nishimoto
authors.affiliation: Department of Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Inoue
authors.affiliation: Department of Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Seishi
authors.initials: S
authors.lastname: Nakatsuka
authors.affiliation: Department of Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: Department of Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Kameyama
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, 160-8582, Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Morioka
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D017115:Catheter Ablation; D002648:Child; D004598:Electrosurgery; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D010017:Osteoma, Osteoid / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: Acetabulum; CT guidance; Case report; Heat ablation; Osteoid osteoma