Introduction
This topic covers tumours and cysts of the jaw bones (odontogenic and non-odontogenic) and the common tumour-like reactive lesions of the oral soft tissues, above all the epulis (a nodule on the gingiva). Know which are true neoplasms, which are reactive, and which are locally aggressive.
Odontogenic tumours of the jaw
Odontogenic tumours arise from the tissue that forms teeth: epithelium, ectomesenchyme, or both. They are mostly benign but some are locally aggressive.
Cysts and non-odontogenic bone lesions
- Odontogenic cysts include the radicular cyst (inflammatory, at the root apex; treated in the previous topic), the dentigerous (follicular) cyst around the crown of an unerupted tooth, and the odontogenic keratocyst, which is lined by thin keratinised epithelium and recurs often.
- Fibrous dysplasia: replacement of bone by fibrous tissue with irregular woven bone trabeculae ('Chinese-letter' pattern), usually in the maxilla, in young people; McCune-Albright syndrome in the polyostotic form.
- Central giant cell granuloma: a reactive or neoplastic lesion with osteoclast-like giant cells in a vascular spindle-cell stroma; the jaw version of the lesion that gives the peripheral epulis. Jaw giant-cell lesions also arise in hyperparathyroidism ('brown tumour').
- Osteoma, osteoid osteoma and osteoblastoma (benign bone-forming), osteosarcoma (malignant, the commonest primary malignant bone tumour; in the jaws it tends to occur later in life than in long bones), chondrosarcoma.
- Metastases (breast, lung, kidney) and multiple myeloma (punched-out lytic lesions) can also involve the jaw; Burkitt lymphoma forms a jaw mass in children in endemic Africa.