Symmetrical Fibrous Hyperplasia of the Palate.

Bilateral symmetrical fibrous palate hyperplasia is not a common case in the literature. The cause of this pathological change is not completely known. The development of hyperplasia may also be associated with a genetic mutation in the gingival soft tissue or gingival injury. We present a case of a 47-year-old patient who developed a formation that manifested bilaterally in the hard palate. After the excision, there were no histological elements in the material that indicated aggressive behavior of the formation. The clinical and histological diagnosis was the bilateral symmetrical palate hyperplasia, which is a very rare condition.

Introduction

Fibrous hyperplasia or palate fibroma is a rare benign soft tissue tumor of the hard palate that occurs in about 1.2% of cases in the adult population (, ). In most cases, it appears as a unilateral, solid formation whose diameter rarely exceeds 1 cm. It is covered with a neat palatine mucosa (). Predisposing factors for the formation are genetic heredity, infections with viral agents, consumption of Betel nut, immunodeficiency as well as lack of protein in the diet (). In 3 - 6% of cases, the formation may malignantly alter to squamous cell carcinoma. This may be due to an abnormal response of fibrous tissue to chronic inflammatory irritation (). About 9% of these formations develop from the area of ​​the interdental papilla. The formations are smaller in diameter, occurring more frequently in the female population, between the ages of twenty and thirty. They are usually found on a wide base and the surface color is pink to red (). Differential diagnostic lesion can be characterized as epulis, peripheral ameloblastoma, peripheral gigantocellular granuloma, and pyogenic emerging granuloma or cemento-ossifying fibroma. Also, the formation can be characterized as bilateral hard palate fibromatosis ().

Connective tissue proliferation may be associated with attachment gingival injury, gingival sulcus injury or the occurrence of a foreign body in the sulcus. The development of hyperplasia may also be associated with a genetic mutation in the gingival soft tissue ().

Case report

In our case, a 47-year-old patient developed a formation that manifested bilaterally in the hard palate area and spread all the way to the border with the soft palate. Fibromatous formation appeared 3 years before the examination. Initially, it grew as a small nodule that a year before began to develop into a bulky fibromatous formation larger than 5 cm in diameter on each side. The mass extended from the area of ​​the upper canines on both sides to the border with the soft palate. The formation was palpably hard and connected at a wide base to the palatal artery. It showed no signs of acute inflammation. The surface of the formation was smooth, and it was the same color as the surrounding mucosa. The formation was completely painless. In the health history, the patient did not report any trauma or irritation of the palate in the past three years. She denied any illnesses or allergies, as well as taking any medications.

Patohistological (PHD) analysis of the formation taken from the left side of the palate revealed that it was a fibromatous change per magna, which was removed completely. The size of the change on the left side of the palate measured 2.6 x 1.5 x 0.9 cm and on the right side 3.2 x 2.5 x 2 cm. The formation was constructed on both the left and the right side of an almost acellular hyaline binder, with no observed mitotic or proliferative activity after immunohistochemical staining for Ki-67. The surface of the formation was covered with a multilayered squamous epithelium. There were no histological elements in the material that indicated aggressive behavior of the formation (Figure 1-4).

Figure 1

Symmetric fibromatous hyperplasia

Figure 2

Excision of the formation on the right side of the palate

Figure 3

The size of the formation after excision

Figure 4

Histological presentation of tissue sample

Discussion

The development of symmetrical palate hyperplasia is of unknown etiology and may be associated with various predisposing factors. There are various names in the literature for this formation such as fibrous epulis or calcifying fibroblastic granuloma (). Peripheral fibroids and oral fibromatosis >1 cm in diameter were linked by immunohistochemical analysis to CD34, alpha-smooth muscle actin (a-SMA), vimentin, Ki-67 (Mib1) and transforming growth factor-alpha (TGF-α). TGF-α is thought to be associated with fibroblast proliferation and enhanced fibroblastic activity (). It is clinically difficult to distinguish between a neoplasm and an uncontrolled reactive hyperplasia of fibrous tissue. Trauma and irritation are still considered to be the main predisposing factors for the occurrence of fibromatous formations in the area of ​​the oral cavity (). Eversole and Leider in their study stated that the recurrence was present in 28% of cases, after enucleation of intraosseous ossifying fibroma (). Such formations are difficult to differentiate diagnostically from peripheral giant cell granulomas, fibromas, pyogenic granulomas, neurofibromatosis, schwannoma, lipoma, calcifying odontogenic cysts and several other odontogenic and nonodontogenic cysts ().

In the literature review from 1950 to 2017, different names for formations of similar shapes and appearances are encountered. Hiebert and Brooks used the name hard palate fibroma in 1950 and histopathological analysis of their sample found that the formation contained accumulations of fibroblasts and mature connective tissue cells (). For a similar formation, Beers used the term bilateral palate fibroma with almost identical finding of patohistological (PHD) analysis (). In the period from 2010 to 2017, Di Lorenzo et al.and Palaia called such changes the symmetrical fibrous hyperplasia of the palate and idiopathic symmetrical hyperplasia of the palate (, ).

In 2017 Syed et al. called the change in the palate symmetrical palatal fibromatosis. A histological analysis of the formation describes avascular fibrous tissue with a thin collagen network and a very weak mitotic activity, with minimal accumulation of inflammatory infiltrate (). Vasconcelos et al. in their paper described the formation in a 47-year-old patient as collagen fibroma. It develops bilaterally on the tubercle of the maxilla and spreads to the soft palate. The formation grows slowly and contains fibroblasts and myofibroblasts. The histological pattern was described identically as the PHD finding in our patient (). Mesquita et al. described the case of a 37-year-old patient with a unilateral nodular fibromatous formation on the left side of the palate, extending throughout the left part of the hard and soft palate. A patohistological and immunohistochemical analysis of the case in the capillary endothelium of the sample confirmed positive for Ki-67, vimentin, CD34 marker, as well as the presence of a more abundant inflammatory infiltrate, which was not the case in our patient (). Evans et al. described fibrous formations on the palate as highly limited, solid, independent formations, which do not infiltrate the surrounding bone ().

Conclusion

Bilateral symmetrical palate hyperplasia is a very rare formation. We presented a case report of a 47-year-old woman with the mentioned change. The surface of the formation was smooth, without any ulcerations. Also, it was solid and extended bilaterally from the canine area to the border of the soft palate.

Treatment included an excision of the formation from healthy tissue and removal of the affected periosteum and periodontal ligament. It is necessary to remove all irritating factors, as well as factors that can cause tissue trauma.