Pathology of the Head and Neck

Maxillofacial Skeleton and Teeth Chapter 4 105Table 4.1. Cysts of the jaws [73]Odontogenic cysts – inflammatoryOdontogenic cysts – developmentalNon-odontogenic cystsPseudocystsRadicular cystResidual cystParadental cystDentigerous cystLateral periodontal cystBotryoid odontogenic cystGlandular odontogenic cystOdontogenic keratocyst (keratocystic odontogenic tumour [181])Gingival cystNasopalatine duct cystNasolabial cystSurgical ciliated cystSolitary bone cystFocal bone marrow defectWhen the inflammation mainly involves the periosteum,the disease is called proliferative periostitis, orcalled periostitis ossificans. Histologically, bony trabeculaethat lie in a linear parallel pattern are seen. The interveningstroma is composed of fibrous connective tissuesparsely infiltrated with lymphocytes and plasmacells.4.3 Cysts of the JawsCysts of the jaws are classified into several categories dependingon histogenesis and aetiology. Those that arisefrom odontogenic epithelium are called odontogenic,those that have their source in other epithelial structuresare known as non-odontogenic. Among the odontogeniccysts, developmental and inflammatory typescan be distinguished [73]. By definition, cysts are linedby epithelium. There are, however, also cavities in thejaw lacking such an epithelial investment that are alsodiscussed under this heading. The various entities arelisted in Table 4.1.4.3.1 Odontogenic Cysts –Inflammatory4.3.1.1 Radicular CystFig. 4.3. Schematic drawing showing a bisected mandible. Left toright: examples of a dentigerous cyst, a lateral periodontal cyst anda radicular cyst (drawing by John de Groot)Radicular cysts are located at the root tips of the teeth(Fig. 4.3). They arise from the epithelial rests of Malassezand are the cysts most frequently seen [34, 146].They are lined by non-keratinising squamous epithelium.This epithelial lining may be thin and atrophicor show elongated rete processes. In many cysts,cholesterol clefts with adjacent giant cells occur. Withinthe cyst epithelium, hyaline bodies of various sizeand shape may be present (Fig. 4.4). The specific natureof these so-called Rushton bodies is unclear [95]. Occasionally,the lining squamous cells are admixed withmucous cells or ciliated cells (Fig. 4.5). Sometimes, thehistologic pattern of the radicular cyst is complicatedby extensive intramural proliferation of squamous epithelialnests of varying size, thus mimicking a squamousodontogenic tumour (see Sect. 4.4.1.4) [187]. Thesame histology may be shown by other jaw cysts, in particularwhen there are extensive inflammatory changes.When a radicular cyst is retained in the jaws afterremoval of the associated tooth, the lesion is called aresidual cyst .When complicated by inflammation, radicular cystsmay cause pain and swelling. However, they may also beasymptomatic and fortuitously detected by radiographicexamination of the dentition.