- Discussion:
- also known as fibrous cortical defect;
- most common bone lesion (40% children);
- it results from defect of periosteal cortical bone development which leads to failure of ossification;
-
natural history:
- lesion typically develops in childhood and adolescence;
- during adolescence non ossifying fibroma is an active
stage 2
lesion that persists or enlarges throughout childhood.
- w/ skeletal maturation, NOF becomes latent & either regresses or ultimately ossifies;
- when tumor occupies > 50% of diameter of bone, bone is prone to frx;
- Radiographic Appearance:
- look for well marginated radiolucent lesion, w/ a distinct multilocular appearance;
- lesion is usually irregular & is surrounded by reactive rim of bone:
- look for benign cortical thinning, erosion, slight expansion;
- there are 2 subtypes;
-
fibrous cortical defect;
- more common lesion;
- is small < 0.5 cm radiolucency w/ in cortex w/ sharply defined cortex;
-
metaphyseal defect;
- lesion commonly develops in metaphysis of
distal femu(90%
cases) or the
distal tibia & is eccentrically located;
- located within or adjacent to the cortex;
- may be eccentrically located within the medullary cavity;
- cortex may bulge over the lesion, as lack of remodleing;
- may be surrounded by a well defined thin rim of reactive bone;
- no periosteal reaction is seen unless there has been a frx;
- Histology:
- look for whorled fibrous tissue, foam cells, & occasionally, small elongated
giant cells;
-
diff dx:
- malignant
fibrous histiocytoma;
-
osteosarcoma;
- histiocytic lymphoma;
-
eosinophilic granuloma;
- pyogenic osteomyelitis;
- Frx Management:
- nonossifying fibroma can act as a stress riser in bone which can lead to stress frx w/ heavy running;
- this will result in pain & increase uptake on bone scan;
- in children, closed treatment is the treatment of choice in most cases;
- these fractures fractures are expected to heal with a normal amount of callus, but resolution
of the fibroma may or may not occur;
- intracapsular curettage is usually sufficient to promote healing of lesion, however, the defect may be supplemented
with bone grafts or other stabilization techniques for frx prophylaxis and treatment;
Benign fibrous histiocytoma of bone
Pathological fractures through non-ossifying fibromas. Review of the Mayo Clinic experience.
