Osteofibrous dysplasia is a rare, nonneoplastic condition of unknown etiology that affects the long bones. It frequently is asymptomatic. 
Frangenheim first described the lesion in 1921 and reported it as a congenital osteitis fibrosa.  Subsequently, Kempson reported two cases affecting the tibia of young children and named the lesion ossifying fibroma.  In 1981, Campanacci and Laus studied 35 cases and coined the term osteofibrous dysplasia of the tibia and fibula.  They proposed this term as a replacement for ossifying fibroma because of the supposed congenital origin of the condition, the histologic resemblance to fibrous dysplasia, and the apparent exclusive involvement of the tibia and fibula.  Osteofibrous dysplasia is occasionally referred to as Campanacci syndrome.
Most lesions of osteofibrous dysplasia affect the cortex of the tibia, predominantly the middle third of the diaphysis. The cortex often is expanded and thinned, with multiple radiolucencies mixed with intervening areas of sclerosis. The second most common site of involvement is the fibula.
Numerous cases of osteofibrous dysplasia affecting the tibia have been reported. Sweet et al reported 30 cases, with ipsilateral fibular involvement in five cases (17%).  In another study of 10 children with tibial lesions, one case (10%) showed ipsilateral fibular involvement. The tibia was affected in each of the 35 cases reported by Campanacci and Laus; ipsilateral involvement of the fibula was noted in four cases (11%), and 22 lesions (63%) affected the middle third of the tibial diaphysis.  Ishida et al found 11 of 12 lesions (92%) in the tibia, with one lesion in the ulna.  Most of these tibial lesions affected the proximal diaphysis.
Bilateral involvement is rare. However, in a study of five children by Ozaki et al, one child presented with bilateral lesions of both ulnae and tibiae.  The tibia was affected in the remaining four children, with one having ipsilateral fibular involvement.
Osteofibrous dysplasia of the mandible, which occurs exclusively in adults, commonly is referred to as ossifying fibroma.
The tibia is a tubular long bone with a triangular shape in cross-section. The bone is surrounded by four fascial compartments. The anteromedial surface lies subcutaneously and therefore has no soft-tissue protection. The primary center of ossification appears at 7 weeks of gestation. The proximal ossific nucleus appears soon after birth and fuses with the metaphysis at approximately age 16 years. The distal ossific nucleus appears at age 2 years and fuses at age 15 years. In some, separate centers of ossification exist for the medial malleolus and tibial tubercle.
The vascular supply to the tibia is provided predominantly by the posterior tibial artery, from which the nutrient artery enters the tibia at the origin of the soleus muscle along the oblique line of the tibia. The nutrient artery of the tibia has three ascending branches and one descending branch. The distal aspect of the tibia is supplied by periosteal anastomoses that enter the bone adjacent to the ankle joint.
Osteofibrous dysplasia has been postulated to arise from a fibrovascular abnormality. Johnson proposed a relationship between osteofibrous dysplasia and adamantinoma on the basis of a common causative factor—namely, a fibrovascular defect.  According to this theory, osteofibrous dysplasia results from an abnormality in the haversian canals, whereas adamantinoma develops secondary to a defect of intramedullary vasculature.
Komiya and Inoue reported similar findings and suggested a deficiency in blood flow within the periosteum as the etiologic factor in osteofibrous dysplasia.  Bridge et al investigated the cytogenetics of osteofibrous dysplasia.  They reported trisomy 12 in two distinct specimens from a lesion in an 11-year-old boy and trisomy 7, 8, and 22 in another boy. Studies of adamantinoma have revealed trisomy 7 and 12, suggesting a relation between osteofibrous dysplasia and adamantinoma (see Presentation).
Sherman et al reported the coexistence of adamantinoma and osteofibrous dysplasia in the same patient, providing additional evidence of a relation between these two entities.  Several other abnormalities have been found within adamantinoma lesions; consequently, these chromosomal anomalies may not be pathogenetic. [17, 18] On the other hand, Sakamoto et al have shown mutations at the Arg 201 codon in persons with fibrous dysplasia but not in persons with osteofibrous dysplasia, findings that suggest a different pathogenesis for each lesion. 
Gray et al identified germline mutations preventing regulated exon skipping in MET.  They determined that aberrant regulation via the juxtamembrane domain subverted core MET receptor functions that regulate osteogenesis within cortical diaphyseal bone and led to osteofibrous dysplasia.
Osteofibrous dysplasia usually is diagnosed in children younger than 10 years, with a peak incidence in children aged 1-5 years. Several occurrences in newborns have also been reported. [21, 22, 23, 24] Adults diagnosed with de-novo osteofibrous dysplasia have been reported, the oldest patient being age 39 years at diagnosis. 
The reported mean age at diagnosis has been variable. Sweet et al and Ishida et al reported an average age over 10 years. [6, 7] In contrast, Komiya and Inoue, Ozaki et al, and Campanacci and Laus reported an average age younger than 10 years. [4, 8, 14]
No significant sex preponderance has been reported consistently, though several studies have found a slight male predilection. Sweet et al reported 16 males in their 30 patients.  Campanacci and Laus noted that 21 of the 35 patients (60%) in their series were male.  ; this represents the largest reported sex preponderance. In contrast, Park et al reported 38 males and 42 females in their series of 80 patients. 
The natural history of osteofibrous dysplasia is unpredictable.  The growth rate can range from slow to rapid, and spontaneous resolution is possible. Campanacci and Laus reported three common clinical courses, as follows:
Moderate progression, particularly during the first 5-10 years of life
Aggressive growth, with resulting marked deformity
Most commonly, there is continued growth of the lesion until skeletal maturity is reached, with the most rapid period of growth occurring before age 10 years. In most cases, moderate progression is followed by gradual improvement once skeletal maturity is attained.