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.