Mandible-Maxilla
Benign tumors / tumorlike conditions
Juvenile ossifying fibroma

Author: Anthony Martinez, M.D. (see Authors page)
Editor: Kelly R. Magliocca, M.D.

Revised: 6 March 2017, last major update February 2017

Copyright: (c) 2004-2017, PathologyOutlines.com, Inc.

PubMed Search: juvenile ossifying fibroma

Cite this page: Juvenile ossifying fibroma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mandiblemaxillajuvossifyingfibroma.html. Accessed May 25th, 2017.
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:

Soft tissue mass in superior left maxilla (fig. 1)

Radiolucent, poorly circumscribed expansile mass

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

Gross images

Images hosted on other servers:

Left maxilla and left maxillary sinus (fig. 2)

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

Images hosted on other servers:

Spindled-to-
stellate cells with
eosinophilic
cytoplasm (fig. 3)

Cytologic atypia absent (fig. 2)

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