Fibroma (irritation fibroma; traumatic fibroma; focal fibrous hyperplasia; fibrous nodule)

The fibroma is the most common “tumor” of the oral cavity. However, it is doubtful that it represents a true neoplasm in most instances; rather, it is a reactive hyperplasia of fibrous connective tissue in response to local irritation or trauma.

Clinical Features

Although the irritation fibroma can occur anywhere in the mouth, the most common location is the buccal mucosa along the bite line. This site is more prone to irritation due to cusps of the teeth or improper dental restoration leading to tissue injury. The labial mucosa, tongue (figure 1-1) , and gingival also are common sites. It is likely that many gingival fibromas represent fibrous maturation of a preexisting pyogenic granuloma. The lesion typically appears as a smooth-surfaced pink nodule that is similar in color to the surrounding mucosa. In black patients, the mass may demonstrate grayish brown pigmentation.

 

In some cases, the surfaces may appear white as a result of hyperkeratosis from continued irritation. Most fibromas are sessile, although some are pedunculated. They range in size from tiny lesions that are only a couple of millimeters in diameter across; however, most fibromas are 1.5cm or less in diameter. The lesion usually produces no symptoms, unless secondary traumatic ulceration of the surface has occurred. Irritation fibromas are most common in the fourth to sixth decades of life, and the male-to-female ratio is almost 1:2 for cases submitted for biopsy.
 




Figure 1-1 Small fibroma on the tip of the tongue 

Histopathologic Features

Microscopic examination of the irritation fibroma shows a nodular mass of fibrous connective tissue covered by stratified squamous epithelium. This connective tissue is usually dense and collagenized, although in some cases it is looser in nature. The lesion is not encapsulated; the fibrous tissue instead blends gradually into the surrounding connective tissues.

 

The collagen bundles may be arranged in a radiating, circular, or haphazard fashion. The covering epithelium often demonstrates atrophy of the rete ridges because of the underlying fibrous mass. However, the surface may exhibit hyperkeratosis from secondary trauma. Scattered inflammation may be seen, most often beneath the epithelial surface. Usually this inflammation is chronic and consists mostly of lymphocytes and plasma cells.

 

Treatment and Prognosis  

The irritation fibroma is treated by conservative surgical excision; recurrence is extremely rare. However, it is important to submit the excised tissue for microscopic examination because other benign or malignant tumors may mimic the clinical appearance of a fibroma.