Mandible & maxilla

Other benign tumors / tumor-like conditions

Juvenile ossifying fibroma



Topic Completed: 1 February 2017

Minor changes: 17 September 2021

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PubMed Search: juvenile ossifying fibroma


Anthony Martinez, M.D.
Kelly Magliocca, D.D.S., M.P.H.
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Cite this page: Martinez A. Juvenile ossifying fibroma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/mandiblemaxillajuvossifyingfibroma.html. Accessed October 15th, 2021.
Definition / general
  • Juvenile ossifying fibroma (JOF) is a rare variant of ossifying fibroma (OF), a benign fibro-osseous lesion
  • It has aggressive behavior
  • It has two histologic subtypes:
    • Juvenile psammomatoid ossifying fibroma
    • Juvenile trabecular ossifying fibroma
Essential features
  • Diagnosis of JOF is dependent on clinical, radiologic and pathologic correlation
  • JOF, OF, fibrous dysplasia (FD) and osseous dysplasia may show significant histologic overlap particularly on small biopsies, however, clinical / surgical management of these entities is markedly different
  • IHC is typically not useful to distinguish the entities
  • Identifying fibro-osseous lesions which occur in association with hyperparathyroidism-jaw tumor (HJT) syndrome is important, as HJT is associated with development of other tumors, including carcinoma
Terminology
  • Juvenile ossifying fibroma (JOF)
  • Active ossifying fibroma (AOF)
  • Juvenile active ossifying fibroma (JAOF)
  • Juvenile trabecular ossifying fibroma (JTOF)
  • Juvenile psammomatoid ossifying fibroma (JPOF)
Epidemiology
  • The average age of JPOF is younger than conventional OF, with a slight male predominance
    • Most cases occur in patients < 12 years old, though a wide age range has been reported (3 months to 72 years)
  • JTOF primarily affects males, ages 8 - 12
Sites
  • JPOF mainly occurs in the bony walls of the paranasal sinuses
    • Paranasal sinus involvement is overall the most common location for JOF
  • JTOF occurs more often in the maxilla
Etiology
  • Ossifying fibromas are thought to originate from the periodontal ligament
Clinical features
  • Can demonstrate rapid growth, causing local destruction and facial asymmetry
  • Paranasal sinus or orbital bone involvement can cause nasal obstruction, proptosis, exophthalmia and visual changes
  • Some lesions are found incidentally on routine radiographic exams
Diagnosis
  • Diagnosis dependent on clinical, radiologic and pathologic correlation
Radiology description
  • Well circumscribed lesion that can be radiolucent, mixed or radiopaque depending on the degree of calcification and presence of cystic areas
  • On CT, well circumscribed lesion with mixed soft tissue and bone density
    • May have thin "egg shell" periphery of bone
    • Usually unilocular
Radiology images

Images hosted on other servers:

Radiolucent lesion in the right maxilla

Large radiolucent area on right side of molar

Mixed radio-opaque and radiolucent lesion

CT scan

Radiolucent lesion with central radiopacities

Expansile lesion of the left frontal sinus

Prognostic factors
  • Excellent prognosis following complete excision
    • 30 - 58% recurrence rate for incompletely excised tumors
Case reports
Treatment
  • Surgical excision
Clinical images

Images hosted on other servers:

Well defined swelling obliterating the vestibule

Bony hard swelling with vestibular obliteration

Swelling angle ramus area of the mandible

Microscopic (histologic) description
  • Juvenile trabecular ossifying fibroma
    • Cellular fibrous stroma composed of spindled to stellate fibroblastic cells with bands of osteoid without osteoblastic rimming together with immature bony trabeculae surrounded by plump osteoblasts
    • Trabeculae can show an anastomosing or "lattice" pattern
    • Mitoses can be present but without cytologic atypia
  • Juvenile psammomatoid ossifying fibroma
    • Fibroblastic stroma containing ossicles resembling psammoma bodies
      • Ossicles may fuse to form trabeculae showing reversal lines
    • Stroma can be cellular or loose / myxoid
  • Both can have aneurysmal bone cyst type changes
    • Pseudocystic stromal degeneration and hemorrhages
Microscopic (histologic) images

Contributed by Kelly R. Magliocca, D.D.S., M.P.H.

Juvenile trabecular ossifying fibroma



Images hosted on other servers:

Mineralized pieces in the form of trabeculae

Extensive osteoid production

Cellular
connective tissue
with spherical
ossicles

Focally fused ossicles

Structures having
basophilic in center
and eosinophilic
in periphery

Immunohistochemistry
  • Stromal cells positive for RUNX2, an important transcription factor for the osteogenic lineage
    • IHC may not be useful as other entities in differential, such as fibrous dysplasia, are RUNX2 positive
Molecular / cytogenetics description
  • HPRT2 mutations have been found in OF (25 - 50%) associated with hyperparathyroidism-jaw tumor syndrome
Differential diagnosis
  • Ossifying fibroma
    • Conventional OF is more common than JOF
    • May have similar radiographic appearance although conventional ossifying fibroma typically has a thin capsule
    • More commonly occurs in the mandible
  • Fibrous dysplasia
    • Radiographic appearance is usually radiolucent, asymmetric with a "ground glass" appearance that blends into normal bone
    • Histologically, has immature woven bone characterized by "Chinese letters" or "alphabet letters"
      • Bony trabeculae usually without osteoblastic rimming
      • Fibrous dysplasia tends to blend with surrounding bone and this continuity of normal and pathologic bone is not a typical feature of JOF
    • Associated with GNAS mutations
  • Osseous dysplasia
    • Idiopathic process involving the periapical areas of teeth
    • Many different types depending on location and extent of involvement
    • Characterized by replacement of normal bone by metaplastic bone and fibrous tissue
  • Cementoblastoma
    • Neoplasm of cementum intimately involved with tooth root
    • Radiographically is a radiopaque mass with a narrow radiolucent rim (pathognomonic)
    • Histologically, consists of dense cementum-like tissue with reversal lines and fibroblastic stroma
    • Most are in mandible
  • Extra cranial (extra dural) meningioma
    • Psamommatous meningioma variant most likely to create confusion
    • Will be Somatostatin receptor subtype 2A (SSTR2A), EMA and variably PR positive
Additional references
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