Juvenile trabecular ossifying fibroma

Juvenile trabecular ossifying fibroma (JTOF) is a rare, benign but locally aggressive fibro-osseous neoplasm of the craniofacial skeleton, recognized by the WHO as a distinct histological variant of juvenile ossifying fibroma (JOF).[1][2] It arises predominantly in children and young adults, with a predilection for the maxilla and mandible.[3][4] The lesion is characterized by rapid, progressive growth that may simulate malignancy clinically and histologically.[5] On imaging, JTOF typically presents as a well-defined, predominantly radiolucent lesion with scattered calcifications and associated bony expansion.[6] Management centers on surgical excision, with treatment approach guided by lesion size, location, and recurrence status; recurrence rates are notably high following conservative surgery.[1][3]

The WHO classification of head and neck tumors recognizes two histological variants of juvenile ossifying fibroma: juvenile trabecular ossifying fibroma (JTOF) and juvenile psammomatoid ossifying fibroma (JPOF).[1][2] The 2022 WHO update maintains JTOF as a distinct entity within the fibro-osseous lesion category.[2]

• Current accepted names: Juvenile trabecular ossifying fibroma; trabecular juvenile ossifying fibroma (TrJOF/JTOF)
• Historical and alternative terms: "Aggressive ossifying fibroma," "active ossifying fibroma," "juvenile active ossifying fibroma," and "trabecular ossifying fibroma" have all been applied to this entity or to the broader JOF category. These terms remain in older literature but are not preferred in current classification.[1][4]
• The term "cemento-ossifying fibroma" was formerly used for the broader ossifying fibroma group but has been largely abandoned for the juvenile variants.[2][5]

• Age: JTOF predominantly affects children and adolescents, with a peak incidence between ages 8 and 12 years. Patients with JTOF are significantly younger than those with the psammomatoid variant. The reported age range extends from infancy to the third decade, though occasional cases in older adults have been documented.[1][4][7]
• Sex: A slight male predilection is reported, though this has been disputed.[4][8]
• Frequency: JTOF is rare and less common than the psammomatoid variant of JOF.[1][4]
• Anatomic distribution: The maxilla and mandible are the primary sites of involvement. The maxilla is traditionally cited as the site of predilection, though some series have reported a mandibular predominance for both JOF variants. Maxillary lesions may extend into and obliterate the maxillary sinus. Involvement of the paranasal sinuses and orbital bones is less common in JTOF than in the psammomatoid variant. Rare extracranial occurrences have been reported.[1][4][5][6][7][9]

Presentation and symptoms

• The most common presentation is a painless, progressive swelling of the affected jaw, often reaching considerable dimensions before clinical detection.[3][10]
• Growth is characteristically rapid and may be alarming, distinguishing JTOF from conventional ossifying fibroma.[1][5]
• With increasing size, facial asymmetry becomes prominent.[1][4]

Examination findings

• Firm, bony-hard expansion of the affected jaw on palpation
• Overlying mucosa is typically intact
• Maxillary lesions may produce nasal obstruction, epistaxis, or eye displacement (proptosis) when extending into the sinus or orbit[4]

Tempo and complications

• Growth is progressive and sometimes rapidly aggressive, potentially causing local destruction.[4]
• Tooth displacement and obstruction of eruption may occur.[11][12]
• Secondary development of an aneurysmal bone cyst (ABC) is an occasional complication, which may accelerate clinical expansion and produce fluid-fluid levels on imaging. ABC formation in JTOF is rare compared with the psammomatoid variant.[3][8][13]
• Pain, when present, may indicate rapid expansion or secondary ABC.[10]

Location and distribution

• JTOF arises centrally within the maxilla or mandible. Maxillary lesions frequently involve the posterior body and may extend to obliterate the maxillary sinus. Mandibular lesions most commonly affect the body and posterior regions.[4][6][7][10]

Periphery and shape

• The lesion characteristically displays well-defined margins on both conventional radiographs and cross-sectional imaging. Unlike conventional ossifying fibroma, JTOF typically lacks a distinct thin radiolucent capsular line at its periphery on intraoral radiographs.[1][3][6]
• The overall shape is round to ovoid, and associated bony expansion has a spherical configuration.[4][6]
• Margins may occasionally appear partially ill-defined, particularly in larger or more aggressive lesions.[14]

Internal architecture

• The characteristic internal pattern is a predominantly radiolucent lesion with irregular, scattered calcifications. This distinguishes JTOF from the psammomatoid variant, which shows a ground-glass pattern.[4][6]
• Ground-glass opacity can occasionally be present but is uncommon compared with psammomatoid JOF and fibrous dysplasia.[4]
• On cross-sectional imaging, the internal density is heterogeneous, with a mixture of hyper- and hypodense areas.[14]
• The internal appearance evolves with lesion maturity: early lesions may be entirely radiolucent, with calcified foci becoming more apparent over time.[1]
• When a secondary ABC is present, fluid-fluid levels and multicystic areas may be seen within or adjacent to the lesion.[13][15]

Effects on teeth and adjacent structures

• Bone expansion is a hallmark feature, present in the majority of cases.[3]
• Tooth displacement is common, with teeth being pushed away from the expanding mass.[1][12]
• Root resorption is uncommon; most JOFs, including JTOF, do not cause tooth root resorption.[3]
• Maxillary lesions may displace the floor of the orbit, obliterate the maxillary sinus, or extend into the nasal cavity.[4]

Cortical involvement and extent

• The overlying cortex is commonly expanded but intact; cortical perforation is uncommon in the majority of cases.[3]
• Cortical disruption, when present, may be seen in larger or more aggressive lesions and should raise concern for a more aggressive process.[14]
• Despite the locally aggressive clinical behavior, the lesion remains demarcated from surrounding structures without soft-tissue invasion, which is an important distinction from malignancy.[5]

Variants

• Unilocular presentation is most common. Multilocular appearances are rare and are typically associated with secondary ABC formation.[1][3][7][13]
• Mixed radiodensity is the most frequent overall pattern, though the radiolucent-dominant appearance with scattered calcifications is the characteristic signature of the trabecular variant specifically.[6][7]

Medical CT

CT is the preferred cross-sectional modality for evaluating JTOF and allows distinction between the trabecular and psammomatoid variants.[6][16] JTOF presents as a predominantly hypodense (radiolucent) lesion with irregular, scattered internal calcifications and well-defined borders, in contrast to the ground-glass pattern of the psammomatoid variant.[6] CT delineates the corticated border and internal calcified component more clearly than MRI.[16] Assessment of cortical integrity, sinus involvement, and orbital extension is best accomplished with CT.[14][16]

MRI

MRI demonstrates heterogeneous signal intensity in JTOF.[14] MRI is comparable to CT for identifying fluid-fluid levels (indicating secondary ABC) and for delineating the anatomic extent of the lesion, particularly soft-tissue relationships.[15][16] However, MRI does not reliably distinguish between the trabecular and psammomatoid variants and is less effective at characterizing corticated borders and internal calcification.[16] MRI may be useful as a complementary modality when orbital or intracranial extension is suspected.

The differential diagnosis of JTOF centers on other fibro-osseous and bone-forming lesions of the jaws in children and young adults. The predominantly radiolucent appearance with scattered calcifications, well-defined margins, spherical expansion, and rapid growth in a pediatric patient constitute the key diagnostic profile.

The highest-risk diagnostic pitfall is misdiagnosis as osteosarcoma, given the rapid growth, young patient age, and histological features of osteoid production with mitotic activity. Incisional biopsy is essential; the combination of well-defined radiographic margins, absence of periosteal reaction, and histological absence of cytonuclear atypia and abnormal mitoses distinguishes JTOF from osteosarcoma.[5]

Diagnostic microscopic findings

• Highly cellular fibrous stroma composed of spindle-shaped fibroblastic cells[1][5]
• Trabeculae of fibrillary osteoid and woven bone arranged in slender strands, sometimes described as having a "garland-like" pattern[4][5]
• Bony trabeculae are lined by a dense rim of enlarged, plump osteoblasts — a characteristic and diagnostically important feature[1][5]
• Bands of cellular osteoid interspersed with the trabecular bone[5]
• Multinucleated osteoclast-like giant cells are characteristically found scattered within the fibrous stroma[1]
• Mitotic activity is present, particularly in cell-rich stromal areas, accounting for the rapid growth. Importantly, cytonuclear atypia and abnormal mitotic figures are absent — this is the critical distinction from osteosarcoma.[1][5]

Radiologic-pathologic correlation

The predominantly radiolucent appearance on imaging corresponds to the highly cellular fibrous stroma, while scattered calcifications reflect the immature osteoid and woven bone trabeculae. The well-defined radiographic margin correlates with the demarcation between lesional tissue and adjacent bone, though JTOF lacks the distinct fibrous capsule seen in conventional ossifying fibroma.[1][5]

Molecular findings

• Chromosome 12 long-arm rearrangement covering MDM2 and RASAL1 has been identified as a recurrent molecular abnormality in JOF, with a significantly higher frequency in the juvenile variant compared with conventional ossifying fibroma and fibrous dysplasia. This rearrangement may serve as both a diagnostic marker and an indicator of more aggressive behavior.[19]
• SATB2 rearrangements, which define psammomatoid ossifying fibroma, are absent in JTOF, supporting the molecular distinction between the two JOF variants. JTOF retains strong SATB2 protein expression by immunohistochemistry, unlike a subset of psammomatoid cases.[18]
• DNA methylation profiling shows that JTOF clusters with cemento-ossifying fibroma and cemento-osseous dysplasia rather than with psammomatoid ossifying fibroma or fibrous dysplasia, further supporting its distinct biologic identity.[17]
• A recent case report has identified a SATB2-EXOC6B fusion in a JTOF, suggesting that the molecular landscape may be broader than previously recognized.[20]

Surgical treatment

• Enucleation with peripheral ostectomy/curettage is recommended as the first-line surgical approach for both JOF variants, balancing adequate local control against the morbidity of radical resection in young patients.[3][7]
  • Curettage with peripheral ostectomy has demonstrated acceptable recurrence rates in institutional series.[7]
  • Enucleation alone or simple curettage is associated with considerably higher recurrence rates.[3][4]
• Surgical resection (segmental or en bloc) results in the lowest recurrence rates — near-zero in most series — but carries significant morbidity including facial disfigurement and functional impairment, particularly problematic in the pediatric population.[3][7][10]
  • Resection is generally reserved for large, recurrent, or rapidly progressive lesions.[4][7]
  • Reconstruction with free tissue grafting may be required after resection.[21]

Recurrence

• Recurrence rates following conservative surgery range from 30% to 58%, substantially higher than for conventional ossifying fibroma.[1][4]
• Recurrences typically occur within 2–3 years of initial treatment.[4]
• Conservative surgery followed by peripheral ostectomy yields lower recurrence rates than enucleation alone.[3]
• Resection achieves near-complete elimination of recurrence.[3]

Adjuvant therapy

• Adjuvant radiotherapy has been reported in rare cases of recurrent JOF where re-excision carries unacceptable morbidity, though experience is extremely limited.[4]

Surveillance

• Long-term radiographic follow-up is essential given the high recurrence propensity.[1][3]
• Close clinical and imaging surveillance is recommended for at least 3–5 years following treatment, with particular vigilance during the first 2–3 years.[4][10]

Prognostic factors

• Younger patient age and concurrent ABC may be associated with more aggressive behavior.[8]
• Surgical approach is the strongest determinant of recurrence risk.[3][7]
• Despite the locally aggressive behavior and high recurrence rate, JTOF does not undergo malignant transformation.[5]

Pediatric considerations

JTOF predominantly affects children during active craniofacial growth, which introduces unique management challenges. Radical resection, while offering the lowest recurrence risk, may cause significant growth disturbance, facial disfigurement, and dental developmental disruption in young patients.[7][10] A staged approach — initial conservative surgery with peripheral ostectomy, reserving resection for recurrence — is often preferred to minimize morbidity while maintaining acceptable oncologic control.[3][7] Treatment planning should involve a multidisciplinary team including oral and maxillofacial surgery, pediatric dentistry, and reconstructive surgery.[10][21]

Molecular diagnostic considerations

The absence of SATB2 rearrangement and the presence of MDM2/RASAL1 co-amplification on chromosome 12q may assist in distinguishing JTOF from psammomatoid ossifying fibroma and from low-grade osteosarcoma in diagnostically challenging cases.[17][18][19] DNA methylation profiling is an emerging tool that may further refine classification of fibro-osseous tumors with overlapping features.[17]