Published online Jul 18, 2017. doi: 10.5312/wjo.v8.i7.561
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
To investigate non-ossifying fibromas (NOFs) common fibrous bone lesions in children that occur in bones of the lower extremities.
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).
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.
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.
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.