1.      Introduction

 Lipomas are benign neoplasm’s of mesenchymal origin [1] composed of mature adipocytes divided into lobules separated by fibrous septum and surrounded by a thin fibrous capsule [2,3].

They are the most frequent mesenchymal neoplasm’s that affect the human body, being commonly observed in the thorax and in extremities [1]; around 20% in the head and neck region; and only 4 to 5% in the oral cavity [4].

The intraoral sites affected by this tumor include the tongue, floor of the mouth, palate, oral vestibule, and jugal mucosa. The latter two sites are the most common, accounting for 50% of all intraoral cases [5,6].

The etiology of this tumor is uncertain, but endocrine disorders, infections, traumas, alcoholism, and inherited traits are believed to be predisposing factors [6].

This type of tumor is uncommon among children, and individuals older than 40 years tend to be more frequently affected at varying rates. There is no predilection for race and its distribution between genders seems to be balanced, with a slight predominance of male individuals, as pointed out by some studies [6,7].

When lipomas affect the oral cavity, they exhibit a painless increase in size, mobility, soft consistency, and a yellowish color [8]. Most tumors measure 10 to 19 mm; however, their size may be a lot bigger due to their progressive growth [9].

As lipomas are asymptomatic, they are neglected by patients, and many of them only seek medical care when the tumor has reached a large size and is compromising functional activities, such as chewing and speaking, or interfering with the placement of dental prostheses [10].

Given that lipomas do not resolve spontaneously and have a progressive growth, surgical intervention is usually recommended. Treatment of oral lipomas, including all histological types, consists of complete surgical excision. After this procedure, recurrence is rare [4].

The aim of this study is to review the clinical and therapeutic aspects of lipomas, especially those in the oral cavity, and to describe an uncommon clinical case of a 64-year-old patient with a giant facial lipoma.

 2.      Case Report

 NRS, 64-year-old, diabetic and hypertensive female patient presented with increasing facial volume for about 7 years. She complained of sporadic pain and trauma to the region before the development of the tumor. On physical examination, there was a flaccid, mobile lesion measuring approximately 12 cm from the right genial region to the mention, circumscribed to the soft tissues, without hyperalgesia, with evident intraoral and extra oral involvement. Oral mucosal tissue looked normal (Figure 1 A-B). The ultrasound scan revealed a thicker hypoechoic region, not well circumscribed, with lipomatous appearance in subcutaneous planes and more superficial lesion in the anterior jugal mucosa (Figure 1C).

Surgical treatment was indicated and after preoperative tests, the lesion was rejected. After direct incision of the mucosa, a soft yellowish mass was observed. Because of evident surgical distinction between the lesion and the tissues, a blunt dissection was performed until complete excision of the lesion (Figure 2). No vital structures were directly affected, but the dissection eventually showed close contact between the lesion and the skin.

Even though the gross aspect of the lesion was highly suggestive of lipoma, the specimen was sent for histopathological analysis, which did not detect malignancies and confirmed the diagnosis (Figure 3). The patient had an uneventful recovery and did not have any recurrence, as evidenced in her follow-up visit 2 years after the surgery (Figure 4).

3.      Discussion

 The etiology of lipomas is quite controversial, including endocrine disorders, inflammation, and local trauma[7]. Literature reviews suggest that Caucasian men aged 49 to 60 years without a family history of lipoma are the most frequently affected group, with no predilection for the affected side[11,12]. Gender predominance does not appear to be remarkable. In the present report, lipoma affected a female patient.

 These gelatin-like smooth-surfaced tumors are often asymptomatic, mobile, and free of ulcerations. Superficial blood vessels are more evident on the tumor as it develops, owing to distension of the mucosa over the lesion. Despite the discrete yellowish color detected clinically, deep lesions may not interfere in the color of epithelial tissue⁶. Moreover, curiously enough, these tumors tend to float when placed in a 10% formaldehyde solution as they are less dense than the solution [13].

 Due to clinical similarities in some cases, other diagnostic possibilities should be included in the differential diagnosis, such as epidermis and oral lymphoepithelial cysts [14]. While the latter have a smaller size and develop mainly in the first decades of life, they are sub mucosal, mobile, and painless nodules with a light yellow color, thus bearing resemblance to lipomas [6,14]. Therefore, histopathological analysis is still the most accurate method for confirming the diagnosis [14], as observed in the present report.

 Lipomas microscopically differentiate too little from the surrounding healthy adipose tissue. Classically, they are fatty masses, but other mesenchymal elements could be present, producing histological variants, which eventually have a negligible impact on treatment and prognosis. These variants are widely acknowledged and include angiolipoma, pleomorphic lipoma, intramuscular lipoma, and fibrolipoma [5,15].

 These tumors are often found in obese individuals. If calorie intake and body fat are reduced, lipomas do not decrease in size, due to the independent metabolism of these lesions [6].

 Imaging exams have an important diagnostic value. Computed Tomographic (CT) scans are useful in determining the accurate location of the lesion, and they usually reveal a hypodense mass circumscribed by a thin capsule that is not enhanced by contrasting agents [11,12]. CT and ultrasound scans were used as complementary exams in the present study.

 Magnetic resonance is also useful, as the margin of lipomas tends to be clearly visible in this kind of exam. The visualization of the capsule based on the black margin substantially aids in the final diagnosis. Such distinction cannot be made by CT scans [11,12,16].

 Ultrasonography can also be used. It is easy and quick to use, inexpensive, and provides good identification of superficial tissues, which are usually hypoechoic. However, this diagnostic modality has poor image resolution [16].

 This type of lesion is treated preferably by surgical excision [17,18], but some authors have described satisfactory results with the use of electrocautery and laser for removal of intraoral lipomas [19]. Cases of recurrence are uncommon, but in case of intramuscular variants, there could be recurrence, and it is widely known that liposarcomas may develop after recurrent lipomas. Despite the low rates of recurrence after surgical excision, postoperative follow-up is important and the prognosis is good in most cases [18,19]. In the case reported herein, the lesion was totally removed, with no evidence of recurrence after 2 years.

 4.      Final Remarks

 Lipoma is a relatively common pathology in the maxillofacial region, and histopathological analysis plays an essential role in ruling out malignancies. Whenever possible, diagnostic resources help choose the treatment plan and surgical approach which is the most effective method of treatment.

Figure 1(A-C): A) Extra oral tumescence extending from the genial region to the mention. B) Intraoral image showing vestibular bulging. C) Ultrasound scans showing thicker hypoechoic layer, not well circumscribed, and lipomatous aspect in subcutaneous planes.

Figure 2: A) Incision in right oral mucosa for lesion exposure. B) Dissection and determination of lesion borders. C) Total excision of the tumor. D) Gross image of the surgically removed tissue.

Figure 3:A) Low-power photomicrograph showing fatty cells and connective tissues with capillary blood vessels. B) Histological examination showing mature adipocytes.

Figure 4: Extra oral aspect 2 years after the surgery.

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