Maxillary Intraosseous Spindle Cell Lipoma

Maxillary Intraosseous Spindle Cell Lipoma

J Oral Maxillofac Surg 69:e131-e134, 2011 Maxillary Intraosseous Spindle Cell Lipoma S. Marc Stokes, DDS, MSc,* James P. Wood, DMD,† and James T. Cas...

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J Oral Maxillofac Surg 69:e131-e134, 2011

Maxillary Intraosseous Spindle Cell Lipoma S. Marc Stokes, DDS, MSc,* James P. Wood, DMD,† and James T. Castle, DDS, MSc‡ sion did not disclose abnormalities, but palpation showed a doughy consistency of the palatal rugae area. Probing depths ranged from 10 to 15 mm along the lingual surface with minimal hemorrhage. The patient’s general health was good and his medical history was unremarkable, with no history of any form of neoplastic disease. Based on radiographic and clinical examinations, reported patient history, and location of the lesion, localized periodontitis, odontogenic keratocyst (keratocystic odontogenic tumor), ameloblastoma, odontogenic myxoma, early cemento-osseous dysplasia, and central giant cell lesion were considered differential diagnoses before surgical removal. Under local anesthesia, a palatal mucoperiosteal flap was raised, thereby exposing the lesion (Fig 2), which extended palatally and perforated the palatal bone and was found juxtaposed to the surrounding palatal mucosa. Upon exploration, an encapsulated, firm, yellow-white, lobulated lesion was noted to have enveloped the apical region of the maxillary left central incisor but did not specifically involve the apex. A large bone defect was noted lingual to the maxillary left central incisor. In addition, a shallow depression was noted along the palatal bone surface posterior to the prominent lingual bone defect. The soft tissue lesion was surgically enucleated with minimal hemorrhage. After primary closure of the surgical site, the specimen was placed in 10% buffered formalin and sent for histologic review. After an 8-month follow-up, the maxillary left central incisor has continued to remain vital.

Lipomas are benign tumors composed of mature adipose tissue that, in the vast majority of cases, are devoid of cellular atypia and represent the most commonly diagnosed mesenchymal neoplasms.1 Although typically located in subcutaneous regions of the trunk and proximal extremities, soft tissue lipomatous neoplasms of the oral and maxillofacial region are much less frequently encountered.2 Intraosseous lipogenic neoplasms are exceedingly uncommon and are considered among the rarest benign primary tumors of bone. A search within the English-language literature disclosed only 6 previously reported intraosseous maxillary lipomas and 17 intraosseous mandibular lipomas.3-11 We present the first reported case of an intraosseous spindle cell lipoma, which in this instance occurred in the anterior maxilla.

Report of a Case A 35-year-old healthy, Caucasian man who was referred for extraction of the maxillary left central incisor with a diagnosis of a vertical root fracture presented with a solitary, well-circumscribed radiolucency that encompassed the apical one third of the maxillary left central incisor. This radiolucency, which was asymptomatic and of unknown duration, radiographically extended to the median palatal suture and did not include the apex (Fig 1). The patient denied any history of trauma to the area. Clinically, there was detectable expansion of the palatal rugae, but no radiographically demonstrable root resorption was present. The maxillary left central incisor exhibited Class I mobility and was responsive to thermal vitality testing. Clinical percus-

MICROSCOPIC EXAMINATION Examination of microscopic slides stained with hematoxylin and eosin revealed a large soft tissue mass consisting of variably dense fibrovascular connective tissue interspersed with lobules of benign adipose tissue. A prominent myxoid background stroma was noted throughout the specimen (Figs 3, 4). Within this lobular architecture, numerous spindle-shaped cells, ropelike collagen, and scattered mast cells were observed. These spindle cells were devoid of cellular pleomorphism and separated individual lobules and cells of adipose tissue. The histologic features were diagnostic of a spindle cell lipoma of maxillary intraosseous origin.

*Assistant Professor, Department of Oral and Maxillofacial Pathology, Naval Postgraduate Dental School, NMMPT&E, Bethesda, MD. †Staff Dentist, Bavaria Dental Activity, United States Army, Bamberg Dental Clinic, Bamberg, Germany. ‡Professor, Department of Oral and Maxillofacial Pathology, Naval Postgraduate Dental School, NMMPT&E, Bethesda, MD. Address correspondence and reprint requests to Dr Castle: Department of Oral and Maxillofacial Pathology, Naval Postgraduate Dental School, NMMPT&E, 8901 Wisconsin Ave, Bethesda, MD 20889-5611; e-mail: [email protected]

Discussion Benign lipomatous tumors are the most frequently encountered mesenchymal neoplasms of soft tissue and consist of mature adipose tissue with no evidence of cellular atypia.1,5 These tumors typically present as soft tissue masses that are solitary, well-circumscribed, mobile, and slow-growing. Most lipomatous tumors are located in the subcutaneous regions of the back, shoulder, neck, abdomen, or proximal extrem-

This is a US government work. There are no restrictions on its use. Published by Elsevier Inc on behalf of the American Association of Oral and Maxillofacial Surgeons 0278-2391/11/6906-0051$36.00/0 doi:10.1016/j.joms.2011.01.043

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oral and maxillofacial region, classic lipoma and spindle cell lipoma were the most common histologic diagnosis variant rendered.20 These tumors occurred, in order of decreasing frequency, in the parotid region, buccal mucosa, lip, tongue, submandibular region, palate, floor of mouth, and vestibule.20 A search of the English-language literature disclosed only 6 previously reported intraosseous maxillary lipomas and 17 intraosseous mandibular lipomas,3–11 with the present case as the first reported spindle cell lipoma in a maxillary, intraosseous location. Lipogenic tumors are exceedingly rare in bone and are considered among the rarest benign primary tumors of bone, representing approximately 0.1% of all bone tumors.21-23 This finding is somewhat surprising because adipocytes are widely distributed throughout normal bone marrow. Although lipomatous tumors have been reported to involve any portion of the skeleton, a predilection for the metaphysis of the long bones and the calcaneus has been noted.6,24,25 Intraosseous lipomatous tumors most likely share a similar neoplastic patho-etiology mirroring that of

FIGURE 1. Periapical film showing a well-circumscribed radiolucency extending to the median palatal suture and involving the apical one third of the maxillary left central incisor, exclusive of the apex. Stokes, Wood, and Castle. Maxillary Intraosseous Spindle Cell Lipoma. J Oral Maxillofac Surg 2011.

ities.12 These tumors may be encapsulated or diffuse13 and occur more commonly in an older patient population of 40 to 60 years of age and do not appear to exhibit any gender or race predilection. In the most recent classification of benign lipomatous tumors, the World Health Organization has recognized the following categories: classic lipoma, lipoma variants (angiolipoma, chondroid lipoma, myolipoma, spindle cell lipoma, pleomorphic lipoma), hamartomatous lesions, diffuse lipomatous proliferations, and hibernoma.14 Debate has prevailed over whether the various lipomatous tumors represent true benign neoplasms or a localized adipocyte hyperplasia. Several published reports have indicated chromosomal abnormalities, most of which have demonstrated rearrangements involving the 13 to 15 region on the long arm of chromosome 12 as evidence for these being true neoplasms.15-17 Lipomatous neoplasms of the oral and maxillofacial region are much less frequently encountered compared with other sites of the body. Their overall frequency within the oral cavity is estimated to represent 1% to 4.4% of all benign oral lesions.5,18,19 In a recent study evaluating 125 soft tissue lipomas of the

FIGURE 2. A, Mass noted lingual to the maxillary left central incisor before enucleation. B, Surgical defect after enucleation. Note the bone defects lingual to the maxillary left central incisor and the palatal bone with a bone bridge between them. Stokes, Wood, and Castle. Maxillary Intraosseous Spindle Cell Lipoma. J Oral Maxillofac Surg 2011.

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more commonly encountered soft tissue lipomatous entities. Additional proposed etiologic factors have included trauma, infarction, infection, and nutritional imbalances in which medullary adipocytes may accumulate and form a lipomatous mass.3,5,23,26 Lipomatous tumors occurring in the maxillofacial skeleton typically show an insidious, often asymptomatic and rather innocuous behavior. However, depending on anatomic location and size of tumor, reported symptoms have included swelling, pain, and paresthesia.6,27,28 Radiographically, they may appear as a well-circumscribed radiolucency, often with a bordering hyperostotic rim. Although central radiopacities caused by fatty necrosis and subsequent calcification have been noted to occur in intraosseous lipomas of the long bones, this finding is uncommon in the gnathic skeleton.3,21,29 According to previous reviews, most reported cases in the gnathic skeleton

FIGURE 4. Numerous spindle cells lacking pleomorphism separating the lipomatous component were observed on a slide stained with hematoxylin and eosin (magnification, ⫻400). Stokes, Wood, and Castle. Maxillary Intraosseous Spindle Cell Lipoma. J Oral Maxillofac Surg 2011.

have occurred in the fourth to fifth decades, which is consistent with the present case, and appear to exhibit a posterior mandibular predilection with a slight predilection for men.3,4,5 Intraosseous maxillofacial lipomas rarely involve tooth roots.5,26 To our knowledge, the present case is the fourth to be associated with a tooth root. Being a rarity, intraosseous maxillofacial lipomas may create a differential diagnostic challenge. Ultimately, a definitive diagnosis can be confirmed only by histopathologic examination because lipomatous variants exist. Therefore, the lesion must be histopathologically differentiated from a well-differentiated liposarcoma whether it is a primary lesion of the jaws or of metastatic origin. Complete surgical removal is the treatment of choice for intraosseous lipomas. No recurrences or malignant dedifferentiation of any intraosseous gnathic lipomas have been reported.

References

FIGURE 3. Slides stained with hematoxylin and eosin show a well-demarcated lobule of benign adipose tissue set within a myxoid background stroma composed of spindle cells. Focal areas of ropelike collagen are also evident. A, Magnification, ⫻20. B, Magnification, ⫻200. Stokes, Wood, and Castle. Maxillary Intraosseous Spindle Cell Lipoma. J Oral Maxillofac Surg 2011.

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