Osteolipoma is a very rare type of lipoma, originating from the mature lamellar bone within the tumor. In this case report, we describe the clinical, radiographic, and histopathological features of a case of osteolipoma in the oral cavity. Our patient was a 58-year-old Iranian female presenting to the Oral and Maxillofacial Clinic of Al-Zahra Hospital, in Isfahan, complaining of a mandibular swelling in the right side. The patient had a history of breast cancer 4 years earlier, which had been treated. She also had been diagnosed with osteoma in the mandibular region 2 years earlier, for which, she had undergone a surgical procedure. Microscopic examination of biopsy specimen revealed mesenchymal tissue composed of mature adipose cells with a lobular pattern, which led to a diagnosis of lipoma with central osseous metaplasia. The patient recovered after surgery. Intraoral lipoma is extremely rare. However, it should be included in the list of differential diagnosis when encountering a lesion composed of adipose tissue in combination with osseous tissue. The prognosis of osteolipoma is similar to that of lipoma, and its management includes complete surgical resection of the tumor. Recurrence has not been reported.
Osteolipoma should be included in the list of differential diagnosis when encountering a lesion composed of adipose tissue in combination with osseous tissue.
Lipoma is the most common benign soft tissue tumor with a mesenchymal origin, which may occur anywhere in the human body [ , ]. Microscopically, lipoma is composed of mature adipose tissue with no cellular atypia, and is often surrounded by a fibrotic connective tissue capsule [ , , ]. Lipoma is more commonly found in the head and neck region, and its occurrence in the oral cavity is uncommon [ ]. Lipomas account for 0.1%–5% of all benign oral tumors. Around 15%–20% of the lipomas occur in the head and neck region while 1%–4% involve the oral cavity [ , , ].
In the oral cavity, lipomas are more commonly seen in the buccal mucosa due to the vicinity to the buccal fat pad, which is rich in adipose tissue. The lips, tongue, palate, vestibule, floor of the mouth, and retromolar pad are among other common sites of lipomas in the oral cavity. On the other hand, salivary glands, gingivobuccal fold, parotid gland, the masseteric region, neck, pharynx and larynx are less commonly involved [ ]. Lipomas often have a slow progression rate, and their etiology is still a matter of debate [ ].
Lipomas are classified into several types, depending on their tissue composition (aside from the adipose tissue), which include fibrolipoma, myelolipoma, leiomyolipoma, chondrolipoma, angiolipoma, and lipoma with cartilaginous or osseous metaplasia, which is a rare type with several other names such as osteolipoma, lipoma with osseous metaplasia, and ossifying lipoma [ , , ].
Intraosseous osteolipoma refers to an osteolipoma that occurs in bone, while an osteolipoma located adjacent to bone is referred to as parosteal or periosteal osteolipoma. Lipomas with ossification that are not attached to the bone (non-attached osteolipomas) have been rarely reported [ ].
Osteolipomas may develop in many anatomical regions such as the scapula, vertebral column, neck, skull, suprasellar area, and cinereum gland [ ]. Osteolipoma of the oral cavity has been rarely reported. De Firth et al. [ ] reported a case of osteolipoma in the buccal mucosa. Herein, we report a case of osteolipoma in the mandibular area in a female patient.
Our patient was a 58-year-old Iranian female that presented to the Oral and Maxillofacial Surgery Clinic of Al-Zahra Hospital in Isfahan complaining of a mandibular swelling in the right side. The patient had a history of breast cancer 4 years earlier, which had been treated. She had been diagnosed with osteoma in the same mandibular region 2 years earlier for which, she had undergone a surgical procedure.
Microscopic evaluation: incisional biopsy
Sections showed a tumor composed of dense, mature lamellar bone. The stroma was composed of adipose cells. There was no evidence of malignancy.
Two years after treatment of osteoma, the patient presented with a right-side mandibular swelling ( Fig. 1 ).
The patient underwent computed tomography (CT) ( Fig. 2 ) and panoramic radiography ( Fig. 3 ), preoperatively. The panoramic radiograph revealed a lesion, which seemed to be an intrabony lesion around the mandibular right second molar root. The preoperative CT scan showed an area with 35-mm diameter in the soft tissue of the right cheek composed of several calcifications next to each other independent of the mandible; however, an enhancing mass was not detected.