Updated: 6/21/2021

Non-Ossifying Fibroma

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https://upload.orthobullets.com/topic/8027/images/Case B - femur - xray - Parsons_moved.png
https://upload.orthobullets.com/topic/8027/images/Case B - femur - bone scan - Parsons_moved.png
https://upload.orthobullets.com/topic/8027/images/5a_moved.jpg
https://upload.orthobullets.com/topic/8027/images/Histology A - low power - Parsons_moved.jpg
https://upload.orthobullets.com/topic/8027/images/Histology B - high power - Parsons_moved.jpg
https://upload.orthobullets.com/topic/8027/images/Histology C - low power - Parsons_moved.jpg
  • summary
    • Non-Ossifying Fibromas are benign fibrogenic lesions that result from dysfunctional ossification that are most commonly found in the metaphysis of long bones. Patients typically present between the ages of 5 and 15 with an asymptomatic lesion discovered incidentally on radiographs.
    • Diagnosis is made on radiographs with a characteristic metaphyseal eccentric "bubbly" lytic lesion surrounded by a sclerotic rim.
    • Treatment is observation as most lesions resolve spontaneously.
  • Epidemiology
    • Incidence
      • occurs in 30-40% of skeletally immature children
    • Demographics
      • more common in males (2:1)
      • common in children 5-15 years old
    • Anatomic location
      • metaphysis of long bones
      • 80% in lower extremity
        • distal femur > proximal tibia > distal tibia
        • uncommon in proximal femur, proximal humerus
  • Etiology
    • Mechanism
      • non-ossifying fibroma (NOF) is a benign fibrogenic lesion that is related to dysfunctional ossification
        • one of the most common benign bone tumors in childhood (with osteochondroma)
        • other names
          • metaphyseal fibrous defect
          • nonosteogenic fibroma
          • cortical desmoid
          • fibrous cortical defect
          • fibromatosis
          • fibroxanthoma
    • 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
  • Presentation
    • Symptoms
      • asymptomatic
        • usually found incidentally
      • may present with pathologic fracture
  • Imaging
    • Radiographs
      • diagnostic
      • metaphyseal eccentric "bubbly" lytic lesion surrounded by sclerotic rim
        • cortex may be expanded and thin
        • length > width
      • as bone grows
        • migrates to diaphysis
        • lesions enlarge (1-7cm)
      • as patient approaches skeletal maturity, lesions become sclerotic
      • 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
  • Studies
    • 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
  • Differential
    • Giant cell tumor
      • painful
      • rare in skeletally immature
      • no mineralization
    • Osteosarcoma
      • painful
      • irregular zone of bony destruction with less defined zone of transition
      • periosteal reaction
      • mineralized soft tissue mass
    • Differential of non-Ossifying Fibroma
      "Bubbly" lytic lesion on xray
      Hemosiderin seen on Histology
      Treatment is Observation alone
      NOF
      ABC
      UBC
      PVNS
      Fibrous dysplasia
      Enchondroma
      Osteochondroma
      Eosinophillic granuloma
      Paget's 
  • Treatment
    • Nonoperative
        • indications
          • first line of treatment
          • most lesions resolve spontaneously and progressively reossify as child enters 2nd and 3rd decade of life
        • technique
          • radiographs at 6 and 12 months, then annually until reossified
      • 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 (> 50-75% cortical involvement)
          • increased risk of fracture shown on quantitative CT
  • Complications
    • Pathologic fracture
      • incidence
        • 90% occur in the lower extremity
          • 50% occur in the distal tibia
      • risk factors
        • >50% involvement of transverse diameter
        • >33mm length in weight-bearing bones (femur and tibia)
      • treatment
        • cast immobilization
          • indications
            • nondisplaced fractures
  • Prognosis
    • Usually spontaneously resolves
    • No malignant or metastatic potential
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(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?

QID: 4633
FIGURES:
1

Enchondroma, observation

4%

(213/4754)

2

Enchondroma, surgical biopsy

1%

(57/4754)

3

Nonossifying fibroma, observation

89%

(4236/4754)

4

Nonossifying fibroma, surgical biopsy

1%

(56/4754)

5

Aneurysmal bone cyst, curettage and bone grafting

4%

(173/4754)

L 1 A

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(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?

QID: 3206
FIGURES:
1

Figure B

3%

(69/2072)

2

Figure C

8%

(165/2072)

3

Figure D

5%

(105/2072)

4

Figure E

33%

(683/2072)

5

Figure F

50%

(1035/2072)

L 4 C

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(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:

QID: 529
FIGURES:
1

Non-weight bearing short leg cast

1%

(21/1863)

2

Tumor staging including chest CT, bone scan, MRI of entire bone

2%

(39/1863)

3

Contacting local child protective services

0%

(4/1863)

4

Activities as tolerated, repeat radiographs in 3 to 6 months

93%

(1735/1863)

5

Curettage and allograft bone packing to lesion.

3%

(52/1863)

L 1 B

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(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?

QID: 704
FIGURES:
1

CBC, ESR, CRP with bone aspiration for gram stain and culture

2%

(49/2341)

2

Biopsy with neoadjuvant chemotherapy followed by limb salvage surgical resection and adjuvant chemotherapy

2%

(49/2341)

3

Repeat radiographs in 3 months

89%

(2089/2341)

4

Biopsy with external beam irradiation followed by limb salvage surgical resection

0%

(10/2341)

5

MRI and CT scan of the chest

6%

(129/2341)

L 1 A

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(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?

QID: 207
FIGURES:
1

Reassurance and weightbearing as tolerated

86%

(1326/1547)

2

Needle biopsy

7%

(107/1547)

3

Incisional biopsy

5%

(74/1547)

4

Excisional biopsy

2%

(28/1547)

5

Wide resection and reconstruction

0%

(7/1547)

L 1 C

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(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?

QID: 1138
FIGURES:
1

Endocrine consultation secondary to associated endocrine abnormalities

1%

(10/842)

2

Surgical consultation secondary to associated gastrointestional cancers

1%

(5/842)

3

Short leg cast and non-weight bearing for a minimum of 6 weeks

2%

(14/842)

4

Open biopsy and tumor staging

8%

(67/842)

5

Routine followup of tibial lesion

88%

(740/842)

L 1 C

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