Discussion
Lipomas are the most common benign tumors in almost all parts of the body that contain adipose tissue. They are relatively uncommon in the oral cavity (1-5% of all benign lesions in the mouth). Lipomas can be seen in different parts of the oral cavity. The literature review showed that half of the oral lipomas were related to the buccal mucosa, and the other half were found in the lips, tongue, floor of the mouth, palate, and gingiva. Oral lipomas were seen in all groups of age, but it has been most frequently reported after 40 years of age [5].
According to their histology, the WHO classifies lipomas in several groups: conventional lipomas, fibrolipomas, angiolipomas, pleomorphic lipomas/spindle cells, mixolipomas, condrolipomas, osteolipomas, miolipomas, lipomatosis, lipomatosis of the nerve, lipoblastomas, and hybernomas. Other variants of lipomas than conventional lipoma is rare. As an example, FL, an uncommon variant of lipoma, is particularly rare in the oral cavity (a prevalence rate of only 1/5000 adults in the oral and oropharyngeal region). Its difference from conventional lipoma is in the way that the mature adipose tissue is interspersed by connective tissue bands [6]. FL has been reported to occur in the buccal mucosa, buccal vestibule, and tongue more frequently [7,8]. The reason for reporting our case is the rareness of the fibrolipoma in the mouth, especially in the gingival part of the oral cavity, and the importance of its differential diagnosis.
Lipomas are painless and freely mobile. Because of their thin overlying epithelium, they usually grow at a low rate and can be clinically seen in a semi-lucent yellow color; the presence and degree of the yellow hue depends on the degree and depth of fibrosis. Its consistency varies from soft to firm. This varies because of the depth of the tumor and the distribution and amount of fibrous tissue. Several cases have shown some grades of fluctuation as well. Lipoma and FL both usually have a thin capsule [9].
Regarding histology, FL consists of mature fat cells, which are divided into lobules by fibrous shoots. This lesion is generally oval-shaped [8].
Several cases of FL have been reported until this day (Figure 2). We reviewed 6 cases as described in Table 1. They aged from 25-75 years, and 50% of them, similar to our case, were females.
In common with Iaconetta, Kiehl, and Manjuantha, the lesion of our patient was yellow, capsulated, and movable. Its consistency, other than one case of Manjuantha, which was firm, was similar to our reviewed cases: soft.
In contrast to the other cases present in the literature described by Iaconetta, Kiehl, and Manjuantha, the FL of our patient did not show any mobility. Unlike our case, which was colored pink-red, the lesions described by Iaconetta and Kiehl were yellow.
The size of the lesions of the cases we reviewed was from 1 to 4 cm; similarly, the lesion of our patient measured 1.5 cm. Like Kiehl and Iaconetta’s, our case did not show any pain.
For the management of our patient and all cases we reviewed (Castellani, Iconetta, Kiehl, Manjuantha), the lesions were removed under local anesthesia and sent to the Pathology department for further study about their microscopic characteristics [4,8,10,11].
As already mentioned, lipoma is one of the most common benign tumors in the body. Lipoma (specifically FL) is extremely rare in the oral cavity. This exophytic lesion can also be mistaken with reactive or other tumoral lesions: due to its adhesion to the surrounding tissues and pseudo-infiltrating characteristics of this lesion because of the abundance of collagen and connective tissue, it can cause doubts of differential diagnosis with malignant infiltrating lesions [11,12]. As a result of the lesion’s adherence to the structures that surround it and its pseudo-infiltrating characteristics, a histological exam is necessary to clarify the nature of the neoformation and to resolve any doubt [13]. Therefore, it is mandatory to perform a biopsy and differential diagnosis and eventually diagnose FL carefully. Another importance of diagnosing FL is that this lesion is one kind of tumor; as a result, it has an increased growth potential. FL almost always grows slowly, but diagnosing it soon and performing the necessary management is essential for a better prognosis and patient’s comfort. The treatment for this kind of lipoma in the oral cavity is a surgical incision under local anesthesia. Although commonly a good result can be observed after surgery, follow-up must be performed once in several months (depending on the lesion and patient’s condition) due to its low recurrence rate.
Our study limitations included lack of genetic evaluation and short follow-up duration.
To diagnose accurately, clinical features and microscopic (histological) findings must be considered. FL is a rare benign tumor in the oral cavity with an increased growth potential compared to classical lipoma. It has a low chance of recurrence.
Lesions that look clinically similar to each other may demonstrate different and similar histopathological characteristics; they, therefore, can raise a diagnostic dilemma for a general dentist. Surgical excision may be an elective treatment for FL, but the examination of excised tissue along with consultation with an Oral Pathologist for an accurate diagnosis and careful follow-up is mandatory to provide a successful treatment and prevent any malignant transformation.
Our case adds to the few cases of gingival FL which have been reported in the English literature.
It is essential to document new cases of FL in the English literature so that better and more accurate treatments can be introduced to prevent any malignancy and further damage they may cause.