The fibroma, also referred to as irritation fibroma, is by far the most common of the oral fibrous tumorlike growths. While the terminology implies a benign neoplasm, most if not all fibromas represent reactive focal fibrous hyperplasia due to trauma or local irritation. Although the term focal fibrous hyperplasia more accurately describes the clinical appearance and pathogenesis of this entity, it is not commonly used.
A fibroma may occur at any oral site, but it is seen most often on the buccal mucosa along the plane of occlusion of the maxillary and mandibular teeth as depicted below. It is a round-to-ovoid, asymptomatic, smooth-surfaced, and firm sessile or pedunculated mass. The diameter may vary from 1 mm to 2 cm. The surface may be hyperkeratotic or ulcerated, owing to repeated trauma.
Fibroma of the left buccal mucosa in a 44-year-old man.
Fibromas are most often observed in adults, but they may occur in individuals of any age and either sex.
The clinical differential diagnosis of a fibroma includes giant cell fibroma, neurofibroma, peripheral giant cell granuloma, mucocele, and benign and malignant salivary gland tumors (eg, see Salivary Gland Neoplasms).
Histologically, a fibroma is an unencapsulated, solid, nodular mass of dense and sometimes hyalinized fibrous connective tissue that is often arranged in haphazard fascicles. A mild chronic inflammatory infiltrate may be present. The surface epithelium may be hyperkeratotic, either hyperplastic or atrophic, and it may be ulcerated. Conservative excisional biopsy is curative, and its findings are diagnostic. Recurrence is possible, however, if the offending irritant persists.[1, 2]
Elastofibroma: The elastofibroma is a rare dermatologic pseudotumor most often seen in the subscapular region. Patients tend to be older than 50 years, and some studies show a female predominance. A single case of oral elastofibroma has been reported. A 56-year-old woman presented with an asymptomatic, 2-cm, firm, well-circumscribed mass in the floor of her mouth. The lesion was conservatively excised and had not recurred after a 2-year follow-up. Histologically, the elastofibroma consists of collagen fibers and coarse elastic fibers that can be demonstrated with elastin stain.[3, 4]
Sclerotic fibroma: The sclerotic fibroma was first described as a component of Cowden syndrome. It is an uncommon benign fibrous neoplasm that occurs most commonly in the skin and may be solitary or multifocal. Both sporadic sclerotic fibromas and those associated with the syndrome have also been described in the oral cavity, mainly in the buccal and labial mucosa. The tumor is a well-delineated but unencapsulated mass of densely collagenized, hypocellular fibrous tissue with a storiform pattern and prominent clefts between collagen bundles. The tumor cells are CD34 and vimentin positive.
The fibromatoses represent a group of infiltrating fibrous proliferations with a biologic behavior and microscopic appearance intermediate between those of benign fibrous lesions and fibrosarcomas. In the head and neck region, they are sometimes referred to as juvenile or aggressive juvenile fibromatoses. Patients of any age may be affected, but three quarters of all cases are diagnosed when the patient is younger than 10 years. No significant sex predilection is apparent.
The most frequent site of occurrence is the soft tissues adjacent to the mandible. Intraoral presentations are rare, but they most often involve the tongue or buccal mucosa. Lesions appear as firm, painless, poorly demarcated masses with a variable growth rate. They are locally aggressive and often cause resorption of the underlying bone when present. A desmoplastic fibroma occurring within the medullary cavity of bone is considered to be the intraosseous counterpart of the soft tissue fibromatosis.
The differential diagnosis of a soft tissue fibromatosis is myofibroma and rhabdomyosarcoma.
Microscopically, fibromatosis is characterized by a poorly delineated, infiltrating cellular proliferation of mature spindle cells arranged in streaming and interlacing fascicles. Collagen production is usually prominent. Infiltration of the adjacent structures is common at the periphery, but cellular atypia is not present.
Treatment consists of wide excision. The reported recurrence rate of 24% for oral fibromatosis is considerably lower than the 50-70% rate reported for fibromatoses of the entire head and neck region.
Gingival fibromatosis deserves separate consideration. It may be hereditary, idiopathic, or drug induced. The hereditary and idiopathic forms manifest as isolated or diffuse firm, noninflammatory enlargements of the keratinized gingiva. Although the process is typically nonpainful, the enlarged gingiva may eventually cover large portions of the clinical crowns of teeth and erode the underlying bone. Recurrence is common following surgical excision. The hereditary form may also manifest as a component of a larger complex syndrome (eg, gingival fibromatosis with hypertrichosis syndrome, Zimmermann-Laband syndrome, Cross syndrome). Both the idiopathic and hereditary forms are rare, limited to the gingiva, and most often affect children. Drug-induced gingival overgrowth has been associated with systemic use of phenytoin, cyclosporin, and calcium channel blockers.
Oral fibroma is a common benign scar-like reaction to persistent long-standing irritation in the mouth. It is also known as traumatic fibroma, focal fibrous hyperplasia, fibrous nodule or oral polyp.
Oral fibroma is most commonly seen in older adults but can occur at any age. It affects 1-2% of adults.
It is usually due to chronic irritation such as:
cheek or lip biting
rubbing from a rough tooth
dentures or other dental prostheses
Clinical features of oral fibroma
Oral fibroma presents as a firm smooth lump in the mouth. It is usually the same colour as the rest of the mouth lining but is sometimes paler or, if it has bled, may look a dark colour. The surface may be ulcerated due to trauma, or become rough and scaly. It is usually dome-shaped but may be on a short stalk like a polyp (pedunculated). If it has developed under a denture it may be flat with a leaf-like shape.
The commonest location for an oral fibroma is on the inside of the cheek where the upper and lower teeth meet. Other common sites include the sides of the tongue, gums and inside the lower lip.
Apart from the feel and appearance, oral fibromas do not cause any symptoms. Oral fibromas develop over weeks or months to reach a maximum size usually about 1cm in diameter, but can sometimes be larger.
Oral fibroma is usually a solitary lesion. When there are many lesions, associated diagnoses need to be considered including tuberous sclerosis, Cowden syndrome, familial fibromatosis and fibrotic papillary hyperplasia of the palate.
Oral fibromas do not develop into oral cancer.
In addition to the irritation fibroma, there are a number of other well-recognised types of oral fibroma:
giant cell fibroma
myofibroma and myofibromatosis
peripheral ossifying fibroma
peripheral odontogenic fibroma
How is oral fibroma diagnosed?
The diagnosis of oral fibroma will be suspected clinically when it presents with the usual history and examination findings. A biopsy may be taken to exclude other conditions or to remove the lesion. Histology will then show typical dense fibrous tissue with relatively few cells. The overlying epithelium may be ulcerated, thinned or thickened.
Treatment of oral fibroma
When treatment is required, the only option is surgical excision of the fibroma with narrow margins. It may recur after surgery if the source of irritation continues. It is therefore also important to manage the source of the irritation. Oral fibromas do not disappear without treatment.