Oral lipoma: Case report and review of literature

Key Clinical Message Lipoma is a benign neoplasm that primarily affects the middle‐aged individuals and has a rare oral cavity occurrence. Given its noninvasive behavior and low recurrence rate, surgical conservative management should be regarded as the best therapeutic option. This paper highlights two patients along with their improved conditions following the treatment.


| Histopathological features
The main findings of the histopathological view of both soft tissue and intraosseous lipomas are arrangements of mature adipocytes that are divided into lobules by the connective tissue septae. Usually, a thin fibrous capsule surrounds the tumor. Several types of soft tissue lipoma are described based on microscopic variations. The most common type is fibrolipoma, which is characterized by the presence of the fibrous components adjacent to the fat cells. Other types such

| Clinical presentation
Most lipoma cases are adult patients aged 40-60 years. These tumors are slow-growing, painless, soft, circumscribed, and associated with submucosal nodules with either a sessile or a pedunculated base. 6,16 The color of oral lipomas varies from yellow to pink depending on the depth of the lesion, 9 most of which are about 10 mm in diameter. 1 Most cases of IOL are accidentally diagnosed during a radiographic examination. The symptoms of IOL are different depending on its size, position, evolution, and growth rate. This tumor may be associated with pain, swelling, and numbness. 17,18 Adequate surgical excision without a safe margin, which has a rare recurrence, is the treatment of choice for this tumor. 8,19 2 | CASE PRESENTATION

| Case 1
A 33-year-old woman referred to an orthodontist due to mandibular anterior crowding. While assessing her panoramic radiography (Figure 1), her dentist found a unilocular radiolucent lesion with a well-defined sclerotic lesion that extended from the left mandibular canine to the right canine. She did not have a medical history of the disease. Intraoral and extraoral examinations were normal, and there were no expansion and pain in the palpation region. All mandibular anterior teeth were checked through electrical pulp testing, all of which were vital. The patient was referred to a maxillofacial surgeon for further evaluation. Cone beam computed tomography (CBCT) was requested for the patient. The radiographic examination showed a regular lesion border without any expansion in the buccal and lingual plates, root resorption, or root displacement ( Figure 2). The lesion was biopsied. First, bilateral mental nerve block anesthesia was performed. Then, the envelope flap was raised between the first premolars and the bone was removed by a surgical bur. Next, the lesion was curetted and sent to a pathology center (Figure 3). The histopathological assessment showed a mature adipocyte with an area of hemorrhage but no atypical fat cell. Hence, it was found to be an IOL (Figure 4). In the follow-up visits, there were no complications or recurrence, and the defect was healed properly.

| Case 2
A 25-year-old woman referred to a maxillofacial department. Her chief complaint was painless swelling in the buccal mucosa for about 2 years, which interfered with her dental occlusion. The lesion was about 1.5 cm and mainly soft on palpation ( Figure 5). Excisional biopsy was done under local anesthesia. The incision was about 2 cm and was inferior and parallel to the Stensen's duct ( Figure 6). The lesion was capsulated and completely dissected. The laboratory examination revealed an adipose tissue and a thin capsule surrounding the lesion and pathologic diagnosis showed an intraoral fibrolipoma ( Figure 7). There were no complications during and after the surgery and no sign of recurrence after 12 months.

| MATERIALS AND METHODS
The present study reviewed the literature of the past 10 years on oral and intraosseous lipomas in the PubMed database ( Table 1). The selection criteria included literature reviews, case series, and case reports in human in English language. The articles that did not contain useful information were eliminated. The papers contained information about sex, age, location, and histopathological pattern.
In the present review, the authors presented two cases of oral lipoma.

| RESULTS
A large number of articles were found, from which 77 articles were selected after applying the selection criteria (Table 1). Among the 120 cases, 58 cases were found in men (48.33%) and 62 cases (51.66%) in women. The average age was found to be 47.69 years, indicating that most lesions occurred in the 4th and 5th decades of life.
Buccal mucosa was the most common region for the occurrence of oral soft tissue lipoma, and mandibular body was

F I G U R E 1 Radiograph of a patient with intraosseous lipoma.
This is panoramic view which shows a unilocular lesion in the symphysis of the mandible | 811 DEHGHANI Et Al.
the most common site for oral intraosseous lipoma. Simple lipoma was the most common histopathological pattern in oral soft tissue lipoma. Most authors considered surgical technique as a definitive treatment.

| DISCUSSION
Lipoma is a benign tumor that can occur in any part of the body. Lipoma can be found in both soft and bony tissues. The clinical features of intraoral lipoma can be related to the location of the lesion. They often refer to slow-growing tumors associated with fatty tissue and vary in diameter, which contributes to the possibility of misdiagnosis. 20 There are different reports about the relationship between lipoma and sex. The incidence of oral lipoma has been reported to be identical in the males and females, or male prevalence has been emphasized or vice versa. 21 Bone lesions are often discovered by accident. Radiographic images show unilocular or multilocular radiolucent lesions with a honeycomb or soap bubble appearance and often an osteosclerotic border. 22,23 A definitive IOL cannot be diagnosed by a radiographic image. Computed tomography (CT) and magnetic resonance imaging (MRI) can detect these tumors easily. Despite the availability of all these techniques, histopathology remains the gold standard for diagnosis of lipomas. 24 The differential diagnosis of IOL includes simple cyst, post-traumatic cyst, aneurysmal bone cyst, giant cell granuloma, ameloblastoma, osteoblastoma, arteriovenous malformations, hemangiomas, infarcted bone, chondrosarcoma, and liposarcoma. 25 The differential diagnosis of intraoral lipoma consists of oral dermoid and epidermoid cysts, oral lymphoepithelial cyst, benign salivary gland tumor, mucocele, benign mesenchymal neoplasm, ranula, ectopic thyroid tissue, and lymphoma. Lesions appearing as swelling on the dorsum of the tongue usually mimic hemangioma, lymphangioma, rhabdomyoma, neuroma, and neurofibroma. 26 Complete surgical excision is the main treatment of lipoma. There is no recurrence after adequate excision. Injectable steroids are used to manage soft tissue lipoma, which can cause the atrophy of the adipose tissue and reduce the size of the tumor. Monthly injection of 1:1 mixture of  lidocaine and triamcinolone acetonide is recommended to be administered to the center of the lesion. 26