Stress fractures of the distal femur involving small nonossifying fibromas
in young athletes.
The principal differential diagnosis for this tumor includes FD, intraosseous lipoma, and nonossifying fibroma
. Fibrous dysplasia, first described by Lichtenstein (10) in 1938, is a noninherited developmental anomaly of bone in which normal bone marrow is replaced by a benign proliferation of fibro-osseous tissue.
The histologic features of nonossifying fibroma
with spindle stromal cells, fibrosis, and aggregates of foamy macrophages allow easy separation from GCTs.
accounts for up to 2% of biopsied bone lesions, but in all probability, most cases go undiagnosed.
These include aneurysmal bone cyst, chondroblastoma, nonossifying fibroma
, giant cell reparative granuloma, pigmented villonodular synovitis, giant cell tumor of tendon sheath, and giant cell-rich osteosarcoma.
The histogenesis and classification of fibrohistiocytic lesions involving bone and containing an admixture of fibrous tissue, foam cells, and giant cells are confusing and include several overlapping entities, such as metaphyseal fibrous defect, nonossifying fibroma
, fibrous cortical defect, fibroxanthoma, and benign fibrous histiocytoma (BFH) of bone.
The nonossifying fibroma
(ie, metaphyseal defect) is more cellular with a storiform pattern and characteristically has multinucleated giant cells, xanthoma cells, and hemosiderin pigment--loaded macrophages.
The majority are considered primary lesions; however, up to 30% can be considered secondary tumors arising from chondroblastomas, osteoblastomas, nonossifying fibromas
, and other benign osseous lesions .
(NOFs) are benign fbrogenic lesions caused by an abnormal area of ossifcation and represent one of the most common benign bone tumors in children between 5 to 15 years of age.
Known focal osseous complications include long bone dysplasia with pseudarthrosis, sphenoid wing dysplasia, nonossifying fibromas
of long bones, chest wall deformities (pectus excavatum), and focal, short-segmented scoliosis.