Structural variations of the jaw bones and overlying oral soft tissues are sometimes mistakenly identified as tumors, but they are usually easily recognized as within the range of normal variation for the oral cavity; biopsy in these cases is rarely indicated. Examples of such structural variants are ectopic lymphoid nodules, or “oral tonsils” (small and slightly reddish nodular elevations of a localized area of the oral mucosa as distinct from the pharyngeal mucosa); tori; a pronounced retromolar pad remaining after the extraction of the last molar teeth; localized nodular connective-tissue thickening of the attached gingiva; the papilla associated with the opening of Stensen’s duct; a circumvallate dorsum of the tongue; and sublingual varicosities in older individuals.
Localized nodular enlargements of the cortical bone of the palate (torus palatinus) and jaws (torus mandibularis) occur frequently and are considered to be normal structural variants that are analagous to the spurs encountered on other bones (eg, on the malleoli of the tibia and fibula) (Figure 7-1). The lack of obvious irritants for most tori and the negligible growth of most tori after an initial slow but steady period of development also suggest that they are usually neither inflammatory hyperplasias nor neoplasms. Histologically, tori consist of layers of dense cortical bone-covered periosteum and an overlying layer of thin epithelium, with minimal rete peg development.
Tori may pose a mechanical problem in the construction of dentures; they are frequently traumatized as a result of their prominent position and thin epithelial covering, and the resulting ulcers are slow to heal. Rarely, tori on the palate or lingual mandibular ridge may become sufficiently large to interfere with eating and speaking. Unless a torus is exceptionally large, its surgical removal (when dictated by mechanical concerns or by a patient’s anxiety) is not a major procedure, provided that splints or stents are fabricated beforehand to provide a protective dressing during healing.
Similar nodular growths or exostoses arise on the buccal aspect of the maxillary and mandibular alveolae and must be differentiated from bony hyperplasia secondary to a chronic periapical abscess. Nodular bony enlargements of the alveolus also can occur in fibrous dysplasia and in Paget’s disease, in which they represent superficial evidence of a more generalized bony dysplasia.
The mylohyoid ridge, located just lingual to the third molars, may be traumatized, resulting in ulceration of the overlying mucosa. This focus of ulceration is painful and can be subject to infection, leading to osteomyelitis. Perhaps the most common insult to this area is intubation for general anesthesia.
Biopsy specimens from oral and perioral tissues, like those from any regional tissue, may contain normal structures that are unique to that area, but such structures have occasionally been mistakenly identified as an abnormality or even as a malignancy. For example, the organ of Chievitz (a group of epithelial cell nests typically located adjacent to the temporal fossa and the long buccal nerve) has in a number of cases been incorrectly diagnosed as a perineuronal invasion of cells from an oral carcinoma, leading to a second and unnecessarily wider surgical excision. In similar fashion, pseudoepitheliomatous hyperplasia, an exuberant but common benign proliferation of the oral epithelium, has been overdiagnosed as invasive carcinoma.