Non-ossifying Fibroma

Topic updated on 07/26/16 4:34am
  • Non-ossifying Fibroma (NOF) is a benign fibrogenic lesion that is the most common benign bone tumor in childhood
    • related to dysfunctional ossification
    • prior names include metaphyseal fibrous defect, nonosteogenic fibroma, cortical desmoid, fibromatosis, or xanthoma
  • Epidemiology
    • demographics
      • common in children 5-15 years old (estimated that 30% of children with open physis have a nonossifying fibroma)
    • locations
      • metaphysis of long bones 
      • 80% in lower extremity
        • common locations include the knee (distal femur and proximal tibia) and distal tibia
  • Pathophysiology
    • possibly due to abnormal osteoclastic resorption at the subperiosteal level during remodeling of the metaphysis
  • Associated conditions
    • Jaffe-Campanacci syndrome
      • congenital syndrome of multiple non-ossifying fibromas and
        • cafe au lait pigmentation
        • mental retardation
        • heart, eyes, gonads involved
    • neurofibromatosis
    • familial multifocal NOF
    • ABC
  • Symptoms
    • usually asymptomatic and found incidentally
    • may present with pathologic fracture
  • Radiographs
    • diagnostic
    • metaphyseal eccentric "bubbly" lytic lesion surrounded by sclerotic rim  
    • cortex may be expanded and thin
    • as bone grows
      • migrates to diaphysis
      • lesions enlarge (1-7cm)
    • lesions become sclerotic as patient approaches skeletal maturity
    • avulsion of adductor magnus insertion in the posteromedial aspect of the distal femur may produce a similar looking lesion. 
  • CT
    • quantitative CT shown to be useful in predicting fracture risk
  • Histology
    • classic characteristics are  
      • fibroblastic spindle cells in whirled or storiform pattern (helicopter in wheat field) 
      • fibroblastic connective tissue background
      • numerous lipophages and giant cells 
      • hemosiderin pigmentation 
      • occasional ABC component
  • Nonoperative
    • observation     
      • indications
        • first line of treatment
        • most lesions resolve spontaneously and observation alone is the treatment for most cases 
    • casting
      • indication
        • pathologic fracture
        • can be treated as per the fracture alone (long leg casting for distal femur pathologic fx)
  • Operative
    • curettage and bone grafting
      • indication
        • symptomatic and large lesion
        • increased risk of fracture shown on quantitative CT
Differentials & Groups
"Bubbly" lytic lesion on xray
Hemosiderin seen on Histology
Treatment is Observation alone (1)
Fibrous dysplasia        
Eosinophillic granuloma        
ASSUMPTIONS: (1) assuming aymptomatic and no impending fracture
B. Scan
Case A multiple
Case B femur
Case C tibia
Case D tibia
Case E femur
Case F tibia with fx
Case G tibia
Case H tibia
(1) - histology does not always correspond to case 


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Qbank (8 Questions)

(OBQ12.273) An 18-year-old male presents with leg pain after tripping during a soccer game. He has no history of leg pain or trauma. Which of the following is the most likely diagnosis and recommended treatment for the finding seen in his radiograph in figure A? Topic Review Topic
FIGURES: A          

1. Enchondroma, observation
2. Enchondroma, surgical biopsy
3. Nonossifying fibroma, observation
4. Nonossifying fibroma, surgical biopsy
5. Aneurysmal bone cyst, curettage and bone grafting

(OBQ10.112) A 9-year-old boy injures his ankle while jumping on a trampoline and cannot bear weight on the extremity. A radiograph taken in the emergency room is displayed in Figure A. A biopsy of this lesion would most likely be consistent with which of the following histology slides? Topic Review Topic
FIGURES: A   B   C   D   E   F

1. Figure B
2. Figure C
3. Figure D
4. Figure E
5. Figure F

(OBQ08.143) You are asked to see an 16-year-old patient by his pediatrician after a lesion is found in the child's distal fibula by radiographs taken for a sprained ankle (Figure A). The child is otherwise healthy, active, and has no pain or limitation of motion. Your management should consist of: Topic Review Topic
FIGURES: A          

1. Non-weight bearing short leg cast
2. Tumor staging including chest CT, bone scan, MRI of entire bone
3. Contacting local child protective services
4. Activities as tolerated, repeat radiographs in 3 to 6 months
5. Curettage and allograft bone packing to lesion.

(OBQ07.43) A 6-year-old boy falls off the monkey bar and presents to the emergency room with an abrasion on his knee and mild knee pain. He is able to bear weight without discomfort and has full range of knee motion. A plain radiograph is shown in Figure A. What is the most appropriate next step in management? Topic Review Topic
FIGURES: A          

1. CBC, ESR, CRP with bone aspiration for gram stain and culture
2. Biopsy with neoadjuvant chemotherapy followed by limb salvage surgical resection and adjuvant chemotherapy
3. Repeat radiographs in 3 months
4. Biopsy with external beam irradiation followed by limb salvage surgical resection
5. MRI and CT scan of the chest

(OBQ06.96) A 20-year-old man falls while skiing and complains of knee pain. When he presents to the office 2 weeks later his physical exam is normal and his pain has resolved. Radiographs are shown in Figures A & B. What is the next most appropriate step in management? Topic Review Topic
FIGURES: A   B        

1. Reassurance and weightbearing as tolerated
2. Needle biopsy
3. Incisional biopsy
4. Excisional biopsy
5. Wide resection and reconstruction

(OBQ05.252) A 14-year-old child is referred to your office for evaluation of a tibia lesion found incidentally after a minor ankle injury. A radiograph of the child's ankle is shown in Figure A. What treatment do you suggest? Topic Review Topic
FIGURES: A          

1. Endocrine consultation secondary to associated endocrine abnormalities
2. Surgical consultation secondary to associated gastrointestional cancers
3. Short leg cast and non-weight bearing for a minimum of 6 weeks
4. Open biopsy and tumor staging
5. Routine followup of tibial lesion

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