Osteolipoma of the palate – An unusual presentation

Sir,

Although not common in the mouth, lipoma is the most common benign mesenchymal neoplasia of soft tissues in adults.[1] Around 20% of the cases involve the head and neck region and only 1–4% occur in the oral cavity.[1,2] Osteolipoma is very rare variant of lipoma accounts for less than 1% of all the cases.[3] Oral lipomas mostly occur in the buccal mucosa, floor of the mouth, tongue, and lips. Only two cases of osteolipoma of the palate have been reported in English literature: One was congenital osteolipoma associated with a cleft palate in a 6-year-old male child[4] and the second was reported in a 37-year-old female Nigerian patient.[5] We present a rare case of osteolipoma of the hard palate in a 55-year-old male patient. A 55-year-old male presented with a chief complaint of palatal swelling posterior to the incisive papilla from 4 years. Both the past medical history and systemic signs are not relevant with the case. Extraoral examination did not reveal any abnormality. On intraoral examination a yellowish pink firm-to-hard palatal swelling measuring about 1.5 × 1.5 cm was noted [Figure 1].

Figure 1.

Yellowish pink firm-to-hard palatal swelling

The swelling was nontender on palpation and overlying mucosa was normal in color without showing any signs of ulceration and erythema. On radiographic examination by oclusal radiographs, a patchy area of radiopacity was revealed. On the basis of clinical features, provisional diagnosis of ossifying fibroma was made. The lesion was surgically excised under local anesthesia by raising the mucoperiosteal flap and a soft yellowish white mass measuring 1.5 × 1 cm [Figure 2] was sent for the histopathological examination. Microscopical examination revealed normal bony trabeculae with the features of osteoblastic rimming, surrounded by mature adipocytes with compressed nuclei at the cell border [Figure 3]. Connective tissue septa were found intervening the adipocytes at places [Figure 4]. No dysplastic features were noted. On the basis of all the histopathological features, a final diagnosis of osteolipoma was established. Follow-up visits were uneventful.

Figure 2.

Gross tissue sent for histopathological examination

Figure 3.

Bony trabeculae surrounded by mature adipocytes

Figure 4.

Connective tissue septa intervening adipocytes

Many benign histological variants of lipoma are known and described based on the type of tissue present and predominant in the lesion: Fibrolipoma, angiolipoma, myolipoma, myxolipoma, spindle cell lipoma, osteolipoma, and chondrolipoma.[1,2,3,4,5,6] Lipomas with osseous or cartilaginous metaplasia is a rare histological variant. Osteolipoma is a variant of lipoma that shows osseous metaplasia accounts for less than 1%[4] and is seen at many extra-oral sites including scapula, vertebral spine, neck, skull, suprasellar region, and tuber cinereum.[4,6]

A differential diagnosis suggesting osteolipoma primarily depends on its location. Because of the various anatomic sites reported for this lesion, a very wide range of lesions can be included in the differential diagnosis, such as other benign tumors that may contain bone including teratoma[2]

In addition, tumor calcinosis, ossifying fibroma, central hemangioma, and myositis ossificans should also be considered.[2,6] Soft-tissue sarcomas that can show calcification or ossification include liposarcoma, synovial sarcoma, osteosarcoma, and chondrosarcoma. Soft-tissue chondromas, which are also rare, are frequently mineralized. Also some series showed that osteolipoma mimicked well-differentiated liposarcoma.[4]

The diagnosis of oteolipoma is easy, and surgical excision is the treatment of choice. The prognosis of osteolipoma is favorable like conventional lipomas, but lesions should be monitored carefully and postoperative follow-up is also required as not much information is available pertaining to this rare tumor.