Oral Fibrolipoma: A Rare Case Report

INTRODUCTION

Lipomas are benign tumors composed of mature adipocytes and histopathologically resemble normal adipose tissue, but their metabolism differs in that the lipids present in them cannot be utilized by the body as a source of energy¹.

Lipomas can occur at any site where adipose tissue is normally present². They are commonly seen subcutaneously in the trunk, shoulders and proximal parts of the extremities³ and about 15-20% of cases involve the head and neck region .Only 1-4% of cases affect the oral cavity. Intraoral lipomas represent 1-5 % of all benign tumors occurring in the oral cavity⁴ . 

Lipomas, apart from containing mature adipocytes can sometimes be associated with other connective tissue elements⁵ giving rise to several variants such as fibrolipomas, angiolipoma, chondroid lipoma, myolipoma, intramuscular lipomas, benign lipoblastoma, spindle cell and pleomorphic lipoma and salivary gland lipoma ^4,6 . However, these variants constitute only a small percentage of lipomas occurring in the oral cavity² . Fibrolipoma, one such rare variant of lipoma^1,4,5,6,7 , consists of mature adipose tissue and fibrous connective tissue^4,8 .It is seen predominantly in middle aged females usually involving the buccal mucosa, tongue and lips⁸ . One such rare presentation of oral fibrolipoma occurring in the buccal mucosa in a 42 year old male is reported here.

CASE REPORT

A 42 year old male patient presented with a painless mass of the right buccal mucosa of 8 years duration. It was associated with mild discomfort on mastication. The mass was initially small and was more or less static in size. However, for the last one year, the patient had noticed a significant increase in the size which he attributes to trauma to the facial region in a road traffic accident.

On examination, a well circumscribed, sessile, spherical mass measuring 1.5 cm in diameter was noted on the right buccal mucosa beneath the occlusal plane in relation to 48 .The surface of the lesion was smooth, covered by normal mucosa, non-tender and soft to firm in consistency (Fig 1). The slip sign was not positive. A provisional diagnosis of fibroma was made. Neurofibroma, lipoma and granular cell tumor were considered in the differential diagnosis.

The lesion was surgically excised and was histopathologically evaluated, which revealed normal stratified squamous epithelium, with lobules of adipocytes and fibrous connective tissue septa in the underlying connective tissue. Based on the histopathologic features, a diagnosis of fibrolipoma was made. The patient recovered well and has been kept on a regular follow up. There has been no evidence of recurrence to date.

DISCUSSION

In the oral and maxillofacial region, fibrolipomas are relatively uncommon^1,5,6,7. Furlong et al in his review of 125 cases of oral lipomas, reported only 2 cases of fibrolipoma⁹. Similarly, de Vischer JG et al reported just 19 fibrolipomas from a total of 225⁵ cases , MacGregor, Dyson et al reported 2 fibrolipomas of their 57 cases of oral lipomas and Seldin et al out of their 26 cases, reported 2 cases of fibrolipomas.¹⁰

Oral Fibrolipomas are more common in females⁴, in contrast to lipomas which are more common in males^4,9. However, a few studies have shown an equal distribution between males and females^4,8. Although a wide age range of 3-88 years has been reported^9,11, they usually occur between the 5th and 7th decades of life with a few cases being reported in children⁵.

The present case occurred in a 42 year old which is in accordance to literature, however, it was found in a male patient.

Fibrolipomas commonly occur in the buccal mucosa, buccal vestibule, tongue and retromolar area⁸. It has been opined by some authors that the distribution of adipose tumors in the above areas corresponds to the amount of fat deposits in the oral cavity¹⁰. A pubmed search has revealed cases being reported in the other parts of the oral cavity such as upper and lower lip, base of the tongue, palate, floor of the mouth and parotid region.

They are usually present as solitary, painless submucosal nodules covered by normal mucosa. Superficial tumors demonstrate a yellowish hue. Deep seated tumors cannot be differentiated from other mesenchymal tumors⁵. The size varies and tumors as large as 8 cm have been reported¹². In the present case, fibrolipoma occurred in the buccal mucosa as a solitary, sessile mass measuring 1.5 cm covered by normal mucosa which is in accordance with the previous reports.

The etiology is unclear, but it may be hereditary or traumatic in origin. The other proposed etiologic factors include chronic irritation, endocrine imbalance, and product of degenerated fibromatous tumor or maturation lipoblastomatosis¹. In the present case, trauma probably contributed to an increase in the size of the swelling.

The following lesions namely, fibroma, granular cell tumor, neurofibroma, neurilemmoma, leiomyoma and rhabdomyoma may be considered in the differential dignoses of fibrolipomas occurring in the buccal mucosa (Table 1). However, most of these present with similar clinical features and histopathologic evaluation is mandatory for diagnosis¹³.

Microscopically, the fibrolipoma is composed of lobules of benign adipocytes with broad bands of dense collagen. Like the classic lipoma, it is often well circumscribed and may be thinly encapsulated¹¹ which help in differentiating it from herniated adipose tissue and fibrous polyps with secondary entrapment of adipose tissue⁴. Fibrolipoma must also be differentiated from fibrosarcoma which is characterized by lack of lobular architecture, areas of prominent fibrosis and lipoblasts⁶. In the present case, the lesion was encapsulated, with lobules of mature fat cells interspersed with broad bands of fibrous connective tissue. No evidence of necrosis, mitotic activity and neither lipoblasts were seen.

Computerized tomography (CT), magnetic resonance imaging (MRI) and ultrasonography have also been used for identifying lipomas, although CT and MRI are far superior. Fibrolipomas on MRI appear inhomogeneously hyperintense on T1and T2-weighted sequences, and on contrast-enhanced T1-weighted sequences⁵ .

Fibrolipomas may be effectively managed by surgical excision 15 with a small portion of surrounding normal tissue. Diode laser and narrow hole extrusion technique (NHET), which is a modification of punch biopsy have been suggested as alternative techniques due to certain advantages such as reduced bleeding, no requirement for sutures, faster scar healing etc^6,11.

Recurrence is rare although it can occur after a long interval due to inadequate surgical excision^5,8. Long term follow up is necessary for patients younger than 18 years of age.¹⁴

Complications, although uncommon may occur. Massive fibrolipomas have been reported causing obstruction of the upper respiratory tract apart from dysphagia, difficulty in mastication and speech and dentofacial deformities such as anterior open bite^7,15. The occurrence of these gigantic lipomas could probably be related to the demonstration of increased expression of PCNA and ki-67 suggestive of increased proliferative rate of cells in fibrolipoma. Further, Liposarcoma may occur in long standing cases.⁵

Hence, fibrolipomas must be considered in the differential diagnosis of benign tumors occurring in the oral cavity. Even though, these tumors appear innocuous; histopathologic evaluation of these lesions is advisable since most of the benign tumors appear similar morphologically. This would help in timely management and prevention of complications.