Quick Review for Patients
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Irritation fibroma, or traumatic fibroma, is a common submucosal response to trauma from teeth or dental prostheses and was first reported in 1846 as fibrous polyp and polypus. It is universally understood that the use of the term "fibroma" is not intended in this case to convey neoplastic origin, as is the usual intent of its use for fibrous tumors in other anatomic sites. Found in 1.2% of adults (Table 1), this inflammatory hyperplasia is the most common oral mucosal mass submitted for biopsy and is usually composed of Types I and III collagen. Gingival lesions are also common, although at that location they probably result from chronic infection rather than trauma. A number of variations on the theme of inflammatory fibrous hyperplasia are mentioned in the following discussion.
The irritation fibroma has a 66% female predilection and can occur at any age, but is usually biopsied in the fourth through sixth decades of life. It is extremely rare during the first decade of life. Patients with multiple fibromas may represent cases of familial fibromatosis, fibrotic papillary hyperplasia of the palate, tuberous sclerosis, or multiple hamartoma syndrome (Cowden syndrome). Those with a generalized fibrous overgrowth of the gingival tissues are said to have fibrous gingival hyperplasia or gingival fibromatosis, which is discussed elsewhere in this book.
Within the mouth, buccal, labial and lateral tongue sites account for 71% of all fibromas. The mass may be sessile or pedunculated, and usually reaches its maximum size within a few months (Figures 1 & 2). Seldom does it exceed 1.5 cm. in size and once fully formed it remains indefinitely. It is an asymptomatic, moderately firm, immovable mass with a surface coloration that is most often normal but may show pallor from decreased vascularity, whiteness from thickened surface keratin, or ulceration from recurring trauma.
A fibroma beneath a denture has no room to expand uniformly in all directions and so develops as a flat, pancake-shaped mass with small surface papules along the outer edges. This leaf-shaped fibroma may be associated with an underlying cupped-out area of bony erosion (Figure 3).
Another unique variant of denture-related fibroma, epulis fissuratum (epulis = "mass on the gingiva"), is an irregular, linear, fibrous hyperplasia occurring in the mucosal vestibule or sulcus adjacent to the alveolar ridge, where the edge of a loose-fitting denture chronically pounds into the tissue. The mass runs parallel to the edge of the denture (Figure 4). Eventually, three or more "waves" of fibrous redundant tissue may be seen, with deep grooves between them. The superior edges of these masses may have a line of papules or secondary growths, perhaps explaining why the lesion was first reported in 1858 as "mamillated epulis." The lesion accounts for approximately 3% of submitted oral biopsies and is usually found in persons 40-50 years of age. It is discussed as a separate entity in this book [click here for more detail].
Yet another rather unique fibrous hyperplasia is the giant cell fibroma, discussed as a separate entity elsewhere in this website. Usually a small mucosal mass less than 0.5 cm. in size, this lesion differs from routine fibrous hyperplasia in that it is typically lobulated, has a greater tendency to recur, and has unique fibroblasts. It represents approximately 5% of all oral/pharyngeal fibromas and is similar to the fibrous papule of the face, which is now thought to represent a variant of angiofibroma. The most common sites of occurrence, in descending order of frequency are: gingiva, tongue, palate, and buccal mucosa. This occurs at a younger age than routine irritation fibromas, with almost 70% of lesions reported in persons less than 30 years of age.
The retrocuspid papilla (retrocuspid papule) is a final fibrous oral mass, one which appears to be a unique variation of normal anatomy. It occurs as a small, asymptomatic, firm papule of the lingual aspect of the mandibular cuspid, either on the gingiva or the adjacent oral floor mucosa. The mass is usually sessile but may be pedunculated and is typically bilateral. It is found in the majority of children but in less than 20% of older adults. Biopsied cases are often red and edematous.
Pathology and Differential Diagnosis
Cut surfaces have a dense whitish-gray, glistening appearance (Figure 5). The irritation fibroma is comprised of a dense and minimally cellular stroma of collagen fibers arranged randomly or organized into interlacing fascicles (Figures 6 & 7). The stromal cells are bipolar fibroblasts with plump nuclei and fibrocytes with thin, elongated nuclei and minimal cytoplasm. As with keloids of the skin, the mucosal fibroma may be remarkably avascular, but areas of necrosis are not seen unless associated with overlying mucosal ulceration. Keloids do not, moreover, occur in the mouth.
Usually scattered, mature capillaries are found; often a few of these are dilated. In cases resulting from the slow fibrosis of granulation tissue or pyogenic granuloma, focal areas of edema and neovascularity may be seen in the midportion or lower third of the mass. Occasional lesions may still contain residual granulation tissue, prompting some pathologists to prefer the term fibrotic pyogenic granuloma. Such lesions may be indistinguishable from the angiofibroma of tuberous sclerosis.
The lesional fibrosis typically extends to the overlying stratified squamous epithelium but may be separated from it by a thin layer of normal fibrovascular connective tissue. While usually nonencapsulated, some lesions show a pseudo-encapsulation and may, therefore, be mistaken for neurofibroma or palisaded encapsulated neuroma. Scattered chronic inflammatory cells are seen in small numbers, usually beneath the epithelium or around blood vessels. Occasional fibromas demonstrate extreme elongation of rete processes and are called fibroepithelial polyps by some authorities, presumably because of their similarity to the dermal lesion of that name. These polyps are seen on the tongue in patients with Gorlin syndrome (nevoid basal cell carcinoma syndrome).
The surface epithelium is usually atrophic but may show signs of continued trauma, such as excess keratin, intracellular edema of the superficial layers or traumatic ulceration. The hyperkeratinized epithelium is not dysplastic or precancerous and is essentially a frictional keratosis. Rarely, melanin deposition is seen in the basal layer. This has no diagnostic significance but its presence has led some to refer to such a lesion as pigmented fibroma.
Epulis fissuratum is microscopically similar to routine irritation fibroma except that the chronic inflammatory cells are more numerous and the surface epithelium is much more likely to be ulcerated, especially in the base of the clefts between the redundant folds of tissue. The intact surface epithelium is often quite acanthotic, with occasional lesions showing enough elongation of rete processes to justify a secondary diagnosis of pseudoepitheliomatous hyperplasia [click here for more detail]. The pathologist must be very cautious about misinterpreting this epithelial hyperplasia as well-differentiated squamous cell carcinoma or verrucous carcinoma, especially with samples showing elongated rete processes cut tangentially or at right angles, appearing as separate islands of epithelium deep in the stroma. It is important, in this regard, to understand that carcinoma in association with epulis fissuratum is extremely rare.
Giant cell fibroma differs from routine irritation fibroma in that it contains moderate numbers of large, stellate fibroblasts with large, angular, pale-staining nuclei [click here for more detail]. Some lesional fibroblasts contain two or more nuclei. These cells are most often seen immediately beneath the epithelium and are seldom numerous. They may impart a "glial" appearance to the fibrous stroma and their similarity to giant nevus cells may be remarkable. Giant cells in the dermal counterpart, fibrous papule of the face, express factor XIIIa but not S-100 protein, indicating an origin from fibroblasts rather than melanocytic nevus cells. The angiofibroma of tuberous sclerosis may also demonstrate similar glial-like stroma.
The retrocuspid papule consists of dense collagenic tissue with large, stellate fibroblasts, sometimes with multiple nuclei [click here for more detail]. The stroma often has a whorled pattern and the surface epithelium may demonstrate considerable rete peg hyperplasia; rests of odontogenic epithelium are occasionally noted. Without the latter features, the histopathologic distinction between this lesion and the giant cell fibroma is slight indeed.
Many soft tissue nodules of the mouth have a moderately dense fibrous stroma but contain various nonfibrous components. These components are used to classify the nodule as a distinctly different entity. Scattered islands of benign and innocuous-looking squamous epithelium, for example, are seen in the peripheral squamous odontogenic tumor and the peripheral Pindborg tumor. Islands of benign odontogenic or basaloid epithelium are found in the peripheral odontogenic fibroma, odontogenic gingival epithelial hamartoma, the peripheral ameloblastoma, the peripheral adenomatoid odontogenic tumor, and the peripheral Gorlin cyst.
Nodules with metaplastic or osteoblastic bone production are usually termed peripheral ossifying fibroma, while dark globular cementoid inclusions are seen in the peripheral cementifying fibroma. Cementoid inclusions or dystrophic calcification may be admixed with epithelial islands in the peripheral Pindborg tumor, the peripheral Gorlin cyst or the peripheral adenomatoid odontogenic tumor. Cartilage in the center of a fibrous nodule is seen in the Cutright tumor.
Entrapped minor salivary glands may also be seen in the lower portion of any focal fibrous hyperplasia, this incidental finding must not be confused with adenomatoid hyperplasia or salivary neoplasia. In a similar fashion, herniated buccal fat pad can present as a mass with deep fatty tissue and overlying fibrosis.
Treatment and Prognosis
Irritation fibroma and
other localized fibrous hyperplasias are easily removed by conservative surgical
excision, with no need to remove a margin of surrounding normal mucosa.
Recurrence is unlikely unless the inciting trauma continues or is repeated. The
bony concavity associated with some leaf-shaped fibromas under dentures will
recontour to normal after removal of the offending mass. For epulis
fissuratum the treatment includes both surgical removal and reline or
remake of the offending denture. Giant cell fibroma is
also treated by conservative surgical excision, but it is more likely to recur
than routine irritation fibroma.
References (Chronologic Order)
Note: General references can be found by clicking on that topic to the left.
Tomes J. A course of lectures on dental physiology and surgery (lectures I-XV). Am J Dent Sc 1846-1848; 7:1-68,121-134; 8:33-54,120-147,313-350.
Saurel L. Memoirs upon the tumors of the gums, known under the name epulis. Am J Dent Sc 1858; 8(new series):33-43, 212-231.
Barker DS, Lucas RB. Localized fibrous overgrowth of the oral mucosa. Br J Oral Surg 1967; 5:86-92.
Cutright DE. The histopathologic findings in 583 cases of epulis fissuratum. Oral Surg Oral Med Oral Pathol 1974; 401-411.
Weathers DR, Callihan MD. Giant cell fibroma. Oral Surg Oral Med Oral Pathol 1974; 37:374-384.
Budtz-Jorgensen E. Oral mucosal lesions associated with the wearing of removable dentures. J Oral Pathol 1981; 10:65-80.
Houston GD. The giant cell fibroma: review of 464 cases. Oral Surg Oral Med Oral Pathol 1982; 53:582-587.
Buchner A, Begleiter A, Hansen LS. The predominance of epulis fissuratum in females. Quintessence Int 1984; 15:6799-702.
Bouquot JE, Crout RJ. Odd gums: The prevalence of common gingival and alveolar lesions in 23,616 white Americans over 35 years of age. Quint Internat 1988; 19:747_753.
Buchner A, Merrell PW, Hansen LS, et al. The retrocuspid papilla of the mandibular lingual gingiva. J Periodontol 1990; 61:585-589.
Magnusson BC, Rasmusson LG. The giant cell fibroma – a review of 103 cases with immunohistochemical findings. Acta Odontol Scan 1995; 53:293-296.
Table 1: Gender-specific prevalence rates per 1,000 population for selected oral masses and surface alterations in U.S. adults, ranked by total frequency. Modified from Bouquot JE. Common oral lesions found during a mass screening examination. J Am Dent Assoc 1986; 112:50-57, and Bouquot JE, Gundlach KKH. Oral exophytic lesions in 23,616 white Americans over 35 years of age. Oral Surg Oral Med Oral Pathol 1986; 62:284-291.
* total examined population = 23,616 adults over 35 years of age
Note: To see enlarged photo, click on
the left-hand picture;
Figure 1: The fibroma is a pink mucosal nodule, often on a broad stalk. Here one is seen on the buccal mucosa. [return to text]
Figure 2: Fibromas are often found on the lateral edge of the tongue, as seen here, because of the high risk for trauma at this site. Photo courtesy of Dr. John Dixon, Charleston, West Virginia. [return to text]
Figure 3: A leaf-shaped fibroma is flattened because it grows under a denture. Often it has small papules along the edge of the "leaf." Here the underlying bone has remodeled to produce a concave area for the fibroma to settle into when the denture is in place. [return to text]
Figure 4: Epulis fissuratum. [return to text]
|Figure 5: Cut surface is glistening whitish-gray and fairly uniform in texture. A slight yellowish discoloration toward the left represents area of hemorrhage from recent trauma. [return to text]|
|Figure 6: Stained low-power view of Figure 5 shows the uniform nature of the fibrous stroma and also shows an atrophic surface epithelium. [return to text]|
|Figure 7: The surface epithelium may be normal, as here, or atrophic or hyperplastic. Immediately beneath the epithelium the dense, rather avascular fibrous stroma has few fibroblasts. [return to text]|
|Figure 8: The stroma is typically dense and avascular, as here, with few fibroblasts. [return to text]|