Retrospective Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Jul 18, 2017; 8(7): 561-566
Published online Jul 18, 2017. doi: 10.5312/wjo.v8.i7.561
Non-ossifying fibromas: Case series, including in uncommon upper extremity sites
Akio Sakamoto, Ryuzo Arai, Takeshi Okamoto, Shuichi Matsuda
Akio Sakamoto, Ryuzo Arai, Takeshi Okamoto, Shuichi Matsuda, Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto City 606-8507, Japan
Author contributions: Sakamoto A drafted the manuscript; Arai R and Okamoto T participated in the design of the study; Matsuda S conceived of the study, participated in its design and coordination, and helped draft the manuscript; all authors read and approved the final manuscript.
Institutional review board statement: This study was reviewed and approved by the Ethics Committee of National Hospital Organization, Kokura Medical Center, Kitakyushu city, Japan, where the research was performed.
Informed consent statement: Patients were not required to give informed consent to the study because the analysis used anonymous clinical data that were obtained after each patient had been notified at the home page of National Hospital Organization, Kokura Medical Center that the data could be used for a clinical study.
Conflict-of-interest statement: The authors have no financial relationships to disclose.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Akio Sakamoto, MD, Lecturer, Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Shogoin, Kawahara-cho 54, Sakyo-ku, Kyoto City 606-8507, Japan. akiosaka@kuhp.kyoto-u.ac.jp
Telephone: +81-75-7513366 Fax: +81-75-7518409
Received: January 13, 2017
Peer-review started: January 16, 2017
First decision: March 28, 2017
Revised: April 10, 2017
Accepted: May 3, 2017
Article in press: May 5, 2017
Published online: July 18, 2017
Abstract
AIM

To investigate non-ossifying fibromas (NOFs) common fibrous bone lesions in children that occur in bones of the lower extremities.

METHODS

We analyzed 44 cases of NOF including 47 lesions, which were referred with a working diagnosis of neoplastic lesions. Lesions were located in the upper extremities (1 proximal humerus, 1 distal radius) and the lower extremities (25 distal femurs, 12 proximal and 4 distal tibias, and 4 proximal fibulas).

RESULTS

Three cases had NOFs in multiple anatomical locations (femur and fibula in 1 case, femur and tibia in 2 cases). Overall, larger lesions > 4 cm and lesion expansion at the cortex were seen in 21% and 32% of cases, respectively. Multiple lesions with bilateral symmetry in the lower extremities suggest that these NOFs were developmental bone defects. Two patients suffered from fracture and were treated without surgery, one in the radius and one in the femur. Lesions in the upper extremities (i.e., humerus of a 4-year-old female and radius of a 9-year-old male) expanded at the cortex and lesion size increased with slow ossification.

CONCLUSION

NOFs in the lower extremity had fewer clinical problems, regardless of their size and expansiveness. In these two upper extremity cases, the NOFs had aggressive biological features. It seems that there is a site specific difference, especially between the upper extremity and the lower extremity. Furthermore, NOFs in the radius are predisposed to fracture because of the slender structure of the radius and the susceptibility to stress.

Keywords: Non-ossifying fibroma, Humerus, Radius, Fibula, Upper extremity

Core tip: Non-ossifying fibromas (NOFs) are common lesions in the lower extremities of children. We analyzed 44 cases of NOF including 47 lesions comprising 2 upper extremity cases and 45 lower extremity cases. Larger lesions > 4 cm and lesion expansion at the cortex were seen in 21% and 32% of cases, respectively. Lesions in the upper extremities in the humerus and the radius expanded at the cortical bone, and lesion size increased with slow ossification, suggestive of aggressive biological features. Furthermore, NOFs in the radius are predisposed to fracture because of the slender structure of the radius and the susceptibility to stress.