Benign Tumors
of Oral Cavity
Tumors of the oral cavity are very diversified.
Only a select few can be discussed here. A fibroma may be found on the
gingiva, lips, palate, and buccal mucosa. It is hard or soft and pale or
reddish, depending on the density of collagen and the abundance of vascular
elements. The gingival fibroma (fibrous epulis) is usually derived from the
periosteum. It is sessile or pedunculated, well defined, and slow growing.
The papilloma is soft
and pedunculated or, when arising from an area of leukoplakia, hard with a
warty, keratinized epithelium. The epithelial projections may grow beyond the
basal layer and may occasionally curl inward into the stroma and become fixed
at their bases, suggesting that they are potentially malignant. They are found
in the same areas as the fibromas and also on the tongue.
The hemangioma, either
cavernous or capillary in structure, is primarily seen on the tongue but may
arise in any part of the mouth from blood vessel endothelium. It may be
congenital or familial, or it may develop at a later period in life. Multiple
hemangiomas can occur anywhere in the mucous membrane of the intestinal tract,
but the lip, tongue, gum, and rectum are sites of predilection. The color is
light red to dark purple, with a tendency to blanch on pressure. Some large
hemangiomas appear more globular than flat and are lobulated on their free
mucosal surfaces, with a tendency toward displacement of bone by osteolysis.
Extension occurs through endothelial proliferation along the nourishing blood
vessels, usually more widespread than is apparent on clinical inspection.
Significant blood loss has been reported from incidental minor procedures such
as tooth extractions.
The benign giant cell
tumor, or epulis, is a not uncommon gingival or, more rarely, an
intraosseous growth, which originates from the periodontal membrane or
periosteum and has a tendency to recur unless this tissue is widely excised.
The superficial form is apparently an exaggerated granulation process, with
numerous giant cells eroding the bone trabeculae; older lesions contain more
adult fibroblasts and fewer hemorrhages. Extravasation of erythrocytes
releasing hemoglobin, which is transformed to hemosiderin, explains the
occasional brown color. The central giant cell tumor may show features of resorptive
inflammation but behaves like a neoplasm and may be identical to the giant cell
tumor of the long bones, though it has little relation to giant cell sarcoma.
The tumor can, however, infiltrate bone and displace teeth. It is
nonencapsulated but does not metastasize. Essentially, it is composed of
spindle cells with a varying amount of collagen fibers, hemorrhagic debris, and
multinucleated cells. Occasionally, a giant cell tumor on the gum or in the
bone is a manifestation of hyperparathyroidism.
The so-called pregnancy
“tumor” is a hyperplasia, developing in the course of a chronic gingivitis,
which is not infrequently observed in pregnant women but sometimes also with
other hormonal alterations (e.g., puberty). Bleeding, particularly of the
interproximal papillae, with light raspberry to dusky red coloration, is an
early sign, followed by a hypertrophic swelling of the papillary gingiva,
ranging from a slight bloating to a tumor of 1 to 2 cm. It may envelop more
than one tooth. The growth regresses with proper oral hygiene and adjusted
toothbrush technique, though surgery may be required because of constant
bleeding. Generally, tumors that are not too large disappear after delivery.
The ameloblastoma, sometimes
termed adamantinoma or adamantoblastoma, is an epithelial neoplasm occurring
chiefly in the mandible (region of the third molar, ramus, or premolar, in that
order of frequency); it belongs to the group of odontogenic tumors (as do the
myxoma and cementoma) (not illustrated). According to generally accepted
belief, the ameloblastoma originates from remnants of the enamel or dental
lamina, but from less differentiated cells (preameloblasts) than those
producing a follicular cyst. The tumor is mostly polycystic, sometimes
monocystic, and occasionally solid. It is this solid form that on rare
occasions has been found to metastasize. The growth of this other-wise benign
tumor is very slow. Microcystic infiltration, roentgenologically revealed by
tiny locules or notching, enlarges the jaw; the only sign is often a tiny bony
capsule distending the surrounding tissue. Eventually, expansion into the
orbit, antrum, and even cranium may take place. The most common variety,
microscopi- cally recognizable, is the ameloblastic type, character- ized by
follicles resembling enamel, with its outer layer of cylindrical cells and
stellate reticuloma in the center. Occasionally, solid strands of
undifferentiated cells or sheaths of stellate cells or an accumulation of
squamous and prickle cells may be found. A microscopic descriptive grading of
ameloblastoma is necessary for proper management of each case and for the
choice between local or radical removal. The recurrence rate of ameloblastoma
is extremely high, but true malignancy is extremely low.
Made up of mixed ectodermal
and mesodermal tissue, the odontoma, also odontogenic in origin, may be
a hard or soft tumor, depending upon the presence or absence of calcified
accretions. The hard odontoma is composed of abnormally arranged enamel,
dentin, and cementum, in a soft fibrous matrix that is gradually replaced by
the calcified elements, leaving a capsule. Complex odontomas contain a
bizarre conglomeration of hard structures without finite shape; compound
odontomas include both rudimentary and apparently normal supernumerary
teeth, at times numbering several dozen. These structures may erupt and imitate
the normal dentition.
Myxoma of the jaw (not illustrated), derived from embryonal
tissue of the dental papilla, is also a benign odontogenic tumor, as is the
cementoma, a special form of fibroma, which appears usually at the apices of
the lower anterior teeth. Multiple cementomas appear only in women, suggesting
an estrogenic influence.
Osteoma (not illustrated) is a compact osteogenic
tumor, and fibroosteoma is a diffuse one. Both are slow-growing benign
neoplasms; a conservative surgical approach is used when the tumors may lead to
deformities.
