Table 1 Differential diagnosis: Odondogenic fibroma and similar fibrous lesions of jaws.

Origin

odontogenic ectomesenchyme

Fibroblastic/myofibroblastic

odontogenic ectomesenchyme

Odontogenic epithelium and odontogenic ectomesenchyme

Odontogenic epithelium

Pathology

Interwoven bundles of collagen embedding variable amount of scattered fibroblasts. Many nests and strands of inactive-looking OE** and calcifications can be found [1–3].

Interlaced bundles and whorled aggregates of densely collagenous tissue containing uniform spindled and elongated fibroblasts/myofibroblasts [2].

Stellate and spindle-shaped cells in a rich myxoid or mucoid stroma with few collagen fibrils. Few OE islands may be present [3, 27].

Branching and anastomosing proliferative OE with peripheral rim of columnar cells in a primitive connective tissue stroma without hard tooth formations [23].

Variably sized solid nodules of cuboidal OE conspicuously with duct-like structures. Eosinophilic amorphous material called "tumor droplets" can be found [28, 29].

Presentation ^#

1.5% of odontogenic tumors [4]

Age: 34.9+19.6 [12]

M:F *= 1:2.8 [12]

Maxilla and mandible in equal proportions, being most affected posterior (73.5%) and anterior (73.5%) regions, respectively [5, 11].

Less than 1% of bone tumors [21, 30]

Age: 15.1+12 [12, 30]

M:F = 1:1.2 [7, 12]

15% may be painfull [21]

Locally invasive and aggressive

Almost mandible (84%), and in posterior portion of both jaws [21, 30]

3-20% of odontogenic tumors [4]

Age: 31.3 [31]

M:F = 1:2.3 [27]

25% may be painful [27]

Locally invasive and aggressive

Mandible (63%) at posterior region and maxilla at premolar region [31].

1.6% of odontogenic tumors [3]

Age: 9.6 [23]

M:F = 1.26:1

Expansive growth

Mandible (80.5%) posterior (73.5%) [23].

1.7-7% of odontogenic tumors^{9, OMS}

Age:13.2 [28]

M:F = 1:2.6 [28]

The absence of a tooth is observed

Maxilla (twice mandible) at anterior region (92.3%) [32]

Radiology

Well-defined radiolucency, unilocular in smaller (average of 2.2cm) and multilocular in larger (average of 4.2cm). Pinpoint calcifications may be present in 12% [3].

Well-defined, almost multilocular radiolucency (76%), more likely to involve bone expansion and boundary destruction [21].

Multilocular (60-80%) as "honeycomb", "soap bubble" or "tennis racket" aspect with well-defined borders. Lesions lower than 4.0 cm may be unilocular [22, 27, 31].

Well-defined, uni/multilocular radiolucency, in most cases exhibiting a radiopaque boundary [23, 24].

unilocular radiolucency associated with the crown and often part of the

root of an unerupted tooth, with displacement of neighbouring teeth [28]

Therapy/prognosis

Curettage/excellent

Surgical resection/tendency of recurrence [21]

Surgical resection/tendency of recurrence [22]

Surgical resection/tendency of recurrence; malignant transformation in 11.4% [23, 25].

Curettage/excellent [28, 29, 32]