Describe before you diagnose
- Location: jaw, region, relation to teeth (periapical, pericoronal, interradicular), above or below the mandibular canal.
- Size and number: single or multiple; unilateral or bilateral.
- Borders: well defined and corticated (slow, benign), well defined without cortex, or ill defined (infection or malignancy).
- Shape and locularity: round, scalloped, unilocular or multilocular.
- Internal density: radiolucent, radiopaque or mixed; pattern of calcification.
- Effects on neighbors: tooth displacement, root resorption, cortical expansion or perforation, widened PDL space, loss of lamina dura, canal displacement.
Classic appearances (each is suggestive, not diagnostic)
| Appearance | Consider |
|---|---|
| Multilocular 'soap bubble' in the posterior mandible | Ameloblastoma, odontogenic keratocyst, central giant cell granuloma (anterior mandible in the young), odontogenic myxoma ('tennis racket' septa) |
| Ground-glass, blending into normal bone | Fibrous dysplasia |
| Cotton-wool opacities with hypercementosis | Paget disease of bone |
| Periapical lucency → mixed → opaque at vital mandibular incisors | Periapical cemento-osseous dysplasia |
| Opacity at the apex of a tooth with pulpitis or necrosis | Condensing osteitis (vs idiopathic osteosclerosis at a vital tooth) |
| Radiolucency scalloping between roots, no expansion, young patient | Simple bone cyst |
| Heart-shaped midline anterior maxilla lucency, vital incisors | Nasopalatine duct cyst |
| Well-defined lucency below the mandibular canal near the angle | Stafne (lingual salivary gland) defect |
| Sunburst periosteal bone; symmetrically widened PDL space | Osteosarcoma |
| 'Onion-skin' layers of periosteal bone | Proliferative periostitis (Garré) in a young patient; also Ewing sarcoma |
| Teeth 'floating' in lucent bone | Langerhans cell histiocytosis, severe periodontitis, malignancy |
| Multiple punched-out lucencies | Multiple myeloma |
| Generalized loss of lamina dura, ground-glass bone | Hyperparathyroidism |
Pericoronal lucencies
- A follicular space wider than about 3–5 mm (commonly taught) around an unerupted crown suggests a dentigerous cyst, but OKC, unicystic ameloblastoma and AOT can look the same; biopsy decides.
- A lucency attached at the CEJ favors a dentigerous cyst; one that surrounds the whole tooth or extends past the CEJ (anterior maxilla, young patient, canine) suggests an AOT.
⚠️ Common traps
- Naming a diagnosis before describing the lesion.
- Treating every periapical lucency as endodontic disease without testing vitality (cemento-osseous dysplasia teeth are vital).
- Assuming well-defined means benign in every case: always correlate clinically and biopsy when unsure.
- Overlooking symmetric PDL widening as an early sign of osteosarcoma or scleroderma.
Mini-quiz
- A mixed radiolucent–radiopaque lesion sits at the apices of vital mandibular incisors in a middle-aged Black woman. The most likely diagnosis is:
- A ground-glass lesion of the maxilla blends into normal bone without a clear border. The leading diagnosis is:
- A well-defined radiolucency below the mandibular canal near the angle that does not change over years is most likely:
- Which finding is most worrying for malignancy?
- Symmetric widening of the PDL space around a few mandibular teeth with a 'sunburst' periosteal reaction suggests:
Answer key: 1 A · 2 A · 3 A · 4 D · 5 B