summary Osteofibrous Dysplasia is a rare benign tumor-like condition that primarily affects the cortices of the tibia. The condition typically presents in patients less than 10 years of age with painless anterior shin swelling. Diagnosis is made by a combination of radiographs showing an anterior eccentric lytic tibial lesion and biopsy showing fibroblast proliferation surrounding islands of woven bone with osteoblastic rimming. Treatment is usually observation alone as lesions usually regress and do not cause problems in adulthood. Epidemiology Demographics usually found in younger children (< 10 years old) males>females Anatomic location primarily in anterior tibia Etiology Genetics trisomy 7, 8, 12, 22 have been reported does NOT have Gs alpha activating mutation like fibrous dysplasia has Presentation Symptoms may be asymptomatic painless swelling anterior or anterolateral bowing of the tibia pseudoarthrosis develops in 10-30% of patients Physical exam may have local tenderness over the tibia Imaging Radiographs recommended views AP and lateral of affected area findings anterior eccentric lytic tibial lesion in child that often leads to tibial bowing usually diaphyseal no periosteal reaction confined to anterior cortex radiographic differential includes adamantinoma Studies Histology histology similar to fibrous dysplasia EXCEPT osteoblastic rimming is present fibroblast proliferation surrounding islands of woven bone with osteoblastic rimming mitotic figures are common may have giant cells Differential Adamantinoma Osteofibrous Dysplasia Differential Tibial diaphysis lesion Treatment is Observation alone Osteofibrous dysplasia o o Fibrous dysplasia o Adamantinoma o Eosinophilic granuloma o Enchondroma / Olliers / Maffucci's o Osteochondroma / MHE o NOF /Jaffe-Campanacci syndrome o Paget's o Treatment Nonoperative observation indication first line of treatment alone is the treatment for most patients bracing indication if deformity significant and interfering with walking Operative deformity correction with osteotomy indication rarely needed significant deformity perform after skeletal maturity Prognosis Lesions usually regress and do not cause problems in adulthood