Produção Nacional
Revisado por pares
Osteolipoma: a rare tumor in the oral cavity
2015; Elsevier BV; Volume: 122; Issue: 1 Linguagem: Inglês
10.1016/j.oooo.2015.09.013
ISSN2212-4411
AutoresSheyla Viana Omonte, Bruno Augusto Benevenuto de Andrade, Rosana María Leal, Hermínia Marques Capistrano, Paulo Eduardo Alencar Souza, Martinho Campolina Rebello Horta,
Tópico(s)Soft tissue tumor case studies
ResumoOsteolipoma is a rarely reported histologic variant of lipoma that exhibits bone formation. To the best of our knowledge, only 13 well-documented case reports of osteolipoma in the oral cavity have been published in the English literature. This study presents the clinical, radiographic, and histologic features of an osteolipoma in the oral cavity and reviews the pertinent literature. The patient was a 29-year-old female, who presented with an 8-month history of a painless, progressively enlarging, well-defined, movable submucosal mass in the left posterior buccal mucosa. The lesion had a hard consistency. Imaging findings revealed a spherical radiopacity with an irregular trabecular pattern. The lesion was excised and the diagnosis of osteolipoma was established. No recurrence was observed after a 5-year follow-up. Osteolipoma is a rarely reported histologic variant of lipoma that exhibits bone formation. To the best of our knowledge, only 13 well-documented case reports of osteolipoma in the oral cavity have been published in the English literature. This study presents the clinical, radiographic, and histologic features of an osteolipoma in the oral cavity and reviews the pertinent literature. The patient was a 29-year-old female, who presented with an 8-month history of a painless, progressively enlarging, well-defined, movable submucosal mass in the left posterior buccal mucosa. The lesion had a hard consistency. Imaging findings revealed a spherical radiopacity with an irregular trabecular pattern. The lesion was excised and the diagnosis of osteolipoma was established. No recurrence was observed after a 5-year follow-up. Lipomas are benign mesenchymal neoplasms of soft tissue, which may affect the oral cavity. Previous studies have suggested that 20% of cases occur in the head and neck region, with only 1% to 4% occurring in the oral cavity.1de Castro A.L. de Castro E.V. Felipini R.C. Ribeiro A.C. Soubhia A.M. Osteolipoma of the buccal mucosa.Med Oral Patol Oral Cir Bucal. 2010; 15: e347-e349Crossref PubMed Scopus (29) Google Scholar, 2Fregnani E.R. Pires F.R. Falzoni R. Lopes M.A. Vargas P.A. Lipomas of the oral cavity: clinical findings, histological classification and proliferative activity of 46 cases.Int J Oral Maxillofac Surg. 2003; 32: 49-53Abstract Full Text PDF PubMed Scopus (192) Google Scholar, 3Furlong M.A. Fanburg-Smith J.C. Childers E.L. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004; 98: 441-450Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar Oral lipomas primarily affect the buccal mucosa, floor of the mouth, and lips.2Fregnani E.R. Pires F.R. Falzoni R. Lopes M.A. Vargas P.A. Lipomas of the oral cavity: clinical findings, histological classification and proliferative activity of 46 cases.Int J Oral Maxillofac Surg. 2003; 32: 49-53Abstract Full Text PDF PubMed Scopus (192) Google Scholar, 3Furlong M.A. Fanburg-Smith J.C. Childers E.L. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004; 98: 441-450Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar Histologic variants of lipoma are described on the basis of the predominant type of lesional tissue, including fibrolipoma, angiolipoma, myolipoma, leiomyolipoma, myxolipoma, spindle cell lipoma, osteolipoma, chondrolipoma, and sialolipoma.2Fregnani E.R. Pires F.R. Falzoni R. Lopes M.A. Vargas P.A. Lipomas of the oral cavity: clinical findings, histological classification and proliferative activity of 46 cases.Int J Oral Maxillofac Surg. 2003; 32: 49-53Abstract Full Text PDF PubMed Scopus (192) Google Scholar, 3Furlong M.A. Fanburg-Smith J.C. Childers E.L. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004; 98: 441-450Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar Osteolipoma, a lipoma exhibiting bone formation, is a rarer histologic variant among oral lipomas, accounting for less than 1% of cases described in the literature.4Obermann E.C. Bele S. Brawanski A. Knuechel R. Hofstaedter F. Ossifying lipoma.Virchows Arch. 1999; 434: 181-183Crossref PubMed Scopus (44) Google Scholar, 5Saghafi S. Mellati E. Sohrabi M. Raahpeyma A. Salehinejad J. Zare-Mahmoodabadi R. Osteolipoma of the oral and pharyngeal region: report of a case and review of the literature.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 105: e30-e34Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar, 6Adebiyi K.E. Ugboko V.I. Maaji S.M. Ndubuizu G. Osteolipoma of the palate: report of a case and review of the literature.Niger J Clin Pract. 2011; 14: 242-244Crossref PubMed Scopus (18) Google Scholar Osteolipomas are classified as intraosseous when located in bone and as parosteal or periosteal when located adjacent to bone. Lipomas that exhibit bone formation but are independent of bone tissue (nonattached osteolipomas) have been reported in very few cases.5Saghafi S. Mellati E. Sohrabi M. Raahpeyma A. Salehinejad J. Zare-Mahmoodabadi R. Osteolipoma of the oral and pharyngeal region: report of a case and review of the literature.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 105: e30-e34Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar To the best of our knowledge, only 13 well-documented case reports of osteolipoma in the oral cavity have been published in the English language literature. Due to its rarity, knowledge about this tumor is incomplete. We describe a case of osteolipoma affecting the buccal mucosa. A 29-year-old female patient presented to the Oral Pathology Clinic at Pontifícia Universidade Católica de Minas Gerais with a painless mass in the left buccal mucosa with an 8-month evolution. The patient had no history of trauma in that region. The medical history and systemic review were noncontributory. Physical intraoral examination showed a 1.5 × 1.5 cm, well-defined, movable submucosal mass in the left posterior buccal mucosa, near the retromolar triangle (Figure 1A). The lesion had a yellowish appearance and hard consistency. The overlying mucosa showed telangiectasia but no ulceration or erythema (Figure 1B). Because the mass presented a hard consistency, a radiographic examination was performed. Imaging findings revealed a round area of radiopacity, with an irregular pattern of trabeculae, and no evidence of cortical abnormality or influence on the surrounding structures was found (Figure 2). The clinical differential diagnosis included oral osseous choristoma (soft tissue osteoma), cartilaginous choristoma, osteolipoma, chrondrolipoma, pleomorphic adenoma with ossification, and other salivary gland or connective tissue tumors with dystrophic calcification. It was free from the periosteum and not attached to any adjacent structures, such as the mandibular bone. With the patient under local anesthesia, the lesion was completely excised. It was free from the periosteum and not attached to any adjacent structures, such as the mandibular bone. The surgical specimen was sent to the Oral Pathology Laboratory. Grossly, the resected specimen consisted of a mass measuring 1.8 × 1.5 × 1.2 cm, which was well circumscribed and yellowish with soft and focal hard consistency (Figure 3A). On sectioning, the mass exhibited a yellow soft tissue with various intermixed thin lamellar bony structures and a fibrous capsule (Figures 3B and 3C). Microscopically, the mass presented abundant mature adipose tissue, with no atypia, and was separated by thin fibrous connective tissue septa. Randomly distributed irregular trabeculae of immature bone, with osteoblastic activity, were found throughout the tumor. No foci of hematopoietic cells were observed (Figures 4A-D). The lesion was surrounded by a thin osseous layer and a fibrous capsule (see Figure 4A). The surgical margins were tumor-free. A final diagnosis of osteolipoma was established. The recovery course was uneventful, and no recurrence was detected after a 5-year long follow-up. Lipomas are common benign soft tissue tumors,7Fletcher C.D.M. Unni K.K. Mertens F. World Health Organization of Tumors. Pathology and Genetics of Tumours of Soft Tissue and Bone. International agency for research on cancer Press (IARC), Lyon, France2002Google Scholar, 8Castilho R.M. Squarize C.H. Nunes F.D. Pinto Júnior D.S. Osteolipoma: a rare lesion in the oral cavity.Br J Oral Maxillofac Surg. 2004; 42: 363-364Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar appearing most commonly in areas of the body where adipose tissue is present.9Piattelli A. Fioroni M. Iezzi G. Rubini C. Osteolipoma of the tongue.Oral Oncol. 2001; 37: 468-470Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar The subcutaneous or submucosal region is the usual site, but these can develop between skeletal muscle fibers, on bone surfaces, or within deep soft tissues.7Fletcher C.D.M. Unni K.K. Mertens F. World Health Organization of Tumors. Pathology and Genetics of Tumours of Soft Tissue and Bone. International agency for research on cancer Press (IARC), Lyon, France2002Google Scholar The tumor may undergo a variety of changes. An uncommon change is ossification.1de Castro A.L. de Castro E.V. Felipini R.C. Ribeiro A.C. Soubhia A.M. Osteolipoma of the buccal mucosa.Med Oral Patol Oral Cir Bucal. 2010; 15: e347-e349Crossref PubMed Scopus (29) Google Scholar, 5Saghafi S. Mellati E. Sohrabi M. Raahpeyma A. Salehinejad J. Zare-Mahmoodabadi R. Osteolipoma of the oral and pharyngeal region: report of a case and review of the literature.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 105: e30-e34Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar, 6Adebiyi K.E. Ugboko V.I. Maaji S.M. Ndubuizu G. Osteolipoma of the palate: report of a case and review of the literature.Niger J Clin Pract. 2011; 14: 242-244Crossref PubMed Scopus (18) Google Scholar, 8Castilho R.M. Squarize C.H. Nunes F.D. Pinto Júnior D.S. Osteolipoma: a rare lesion in the oral cavity.Br J Oral Maxillofac Surg. 2004; 42: 363-364Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar, 9Piattelli A. Fioroni M. Iezzi G. Rubini C. Osteolipoma of the tongue.Oral Oncol. 2001; 37: 468-470Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 10Amaral M.B. Borges C.F. de Freitas J.B. Capistrano H.M. Mesquita R.A. Osteolipoma of the oral cavity: a case report.J Maxillofac Oral Surg. 2015; 14: 195-199Crossref PubMed Scopus (10) Google Scholar, 11Godby A.F. Drez P.B. Field J.L. Sublingual lipoma with ectopic bone formation. Report of a case.Oral Surg Oral Med Oral Pathol. 1961; 14: 625-629Abstract Full Text PDF PubMed Scopus (29) Google Scholar, 12Hughes C.L. Intraoral lipoma with osseous metaplasia. Report of a case.Oral Surg Oral Med Oral Pathol. 1966; 21: 576-578Abstract Full Text PDF PubMed Scopus (30) Google Scholar, 13Allard R.H. Blok P. van der Kwast W.A. van der Waal I. Oral lipomas with osseous and chondrous metaplasia: report of two cases.J Oral Pathol. 1982; 11: 18-25Crossref PubMed Scopus (50) Google Scholar, 14Gokul S. Ranjini K.V. Kirankumar K. Hallikeri K. Congenital osteolipoma associated with cleft palate: a case report.Int J Oral Maxillofac Surg. 2009; 38: 91-93Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar, 15Hsu H.H. Lee L.Y. Chang K.P. Pathology quiz case 2. Osteolipoma of the buccal space.Arch Otolaryngol Head Neck Surg. 2012; 138: 97-98Crossref PubMed Scopus (7) Google Scholar, 16Bajpai M. Kumar M. Agarwal D. Agrawal S. Gupta S. Osteolipoma of the palate—an unusual presentation.Natl J Maxillofac Surg. 2014; 5: 250-251Crossref PubMed Google Scholar, 17Raghunath V. Manjunatha B.S. Osteolipoma of floor of the mouth.BMJ Case Rep. 2015; 2015 (pii: bcr2015209883)PubMed Google Scholar To our knowledge, only 13 cases of oral osteolipomas have been reported in the English language literature. Table I summarizes their features.Table IOsteolipomas of the oral cavity previously reported in the English language literature (current case included)AuthorAge (Years)GenderSiteClinical presentationImaging findingsDurationHistopathologyGodby et al.11Godby A.F. Drez P.B. Field J.L. Sublingual lipoma with ectopic bone formation. Report of a case.Oral Surg Oral Med Oral Pathol. 1961; 14: 625-629Abstract Full Text PDF PubMed Scopus (29) Google Scholar54MaleFloor of the mouthPainless and soft mass. Size: 7.0 × 6.0 × 3.0 cm (gross examination)Radiopaque mass (occlusal radiography)1 yearMature adipose tissue, well-formed cancellous bone, fibrous connective tissue and striated muscleHughes CL12Hughes C.L. Intraoral lipoma with osseous metaplasia. Report of a case.Oral Surg Oral Med Oral Pathol. 1966; 21: 576-578Abstract Full Text PDF PubMed Scopus (30) Google Scholar69MaleMandibular buccal vestibulePainless and soft yellowish "walnut-size" massSlight facial asymmetryNo evidence of alterations (radiography)NAFat cells with foci of ossification surrounded by fibrous connective tissueAllard et al.13Allard R.H. Blok P. van der Kwast W.A. van der Waal I. Oral lipomas with osseous and chondrous metaplasia: report of two cases.J Oral Pathol. 1982; 11: 18-25Crossref PubMed Scopus (50) Google Scholar81FemaleMandibular buccal vestibuleFacial asymmetryPainless and hard "walnut-size" massWell defined radiopaque mass with a pattern of irregular trabeculae (occlusal radiography)30-40 yearsHomogeneous adipose tissue containing fibrous septa and irregular trabeculae of lamellar bone without hematopoietic tissuePiattelli et al.9Piattelli A. Fioroni M. Iezzi G. Rubini C. Osteolipoma of the tongue.Oral Oncol. 2001; 37: 468-470Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar49FemaleLateral margin of the tonguePainless and hard massSize: 0.8 cm in diameterNA8 yearsMature adipose tissue containing lamellar bone surrounded by a fibrous pseudocapsuleCastilho et al.8Castilho R.M. Squarize C.H. Nunes F.D. Pinto Júnior D.S. Osteolipoma: a rare lesion in the oral cavity.Br J Oral Maxillofac Surg. 2004; 42: 363-364Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar65FemaleBuccal mucosaPainless and soft yellowish mass Size: 1.0 × 1.0 × 0.8 cm (gross examination)NANAMature fat cells supported by fibrous septa.Focal areas of woven bone surrounded by fusiform-shaped mesenchymal cellsSaghafi et al.5Saghafi S. Mellati E. Sohrabi M. Raahpeyma A. Salehinejad J. Zare-Mahmoodabadi R. Osteolipoma of the oral and pharyngeal region: report of a case and review of the literature.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 105: e30-e34Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar68MaleMandibular buccal alveolar mucosaPainless and hard mass. Size: 1.5 × 1.0 cmNo evidence of cortical abnormality or influence on the surrounding structures (radiography)4 yearsAdipose tissue with foci of lamellar bone surrounded by mesenchymal cellsGokul et al.14Gokul S. Ranjini K.V. Kirankumar K. Hallikeri K. Congenital osteolipoma associated with cleft palate: a case report.Int J Oral Maxillofac Surg. 2009; 38: 91-93Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar6MaleHard palate (associated with cleft of hard and soft palate)Painless and soft mass. Size: 3.0 × 2.0 cmWell-defined hypodense lesion arising with mixed density, showing a well-defined radiodense body (computed tomography)CongenitalLobules of adipose tissue separated by fibrovascular connective tissue septa and showing the presence of mature bonede Castro et al.1de Castro A.L. de Castro E.V. Felipini R.C. Ribeiro A.C. Soubhia A.M. Osteolipoma of the buccal mucosa.Med Oral Patol Oral Cir Bucal. 2010; 15: e347-e349Crossref PubMed Scopus (29) Google Scholar47FemaleBuccal mucosaFacial asymmetryPainless nodule. Size: 1.5 cm in diameterAn irregular and radiopaque structure (radiography of the surgical specimen)1 yearTrabeculae of lamellar bone inside a mature adipose tissue surrounded by thin septa of conjunctive tissueAdebiyi et al.6Adebiyi K.E. Ugboko V.I. Maaji S.M. Ndubuizu G. Osteolipoma of the palate: report of a case and review of the literature.Niger J Clin Pract. 2011; 14: 242-244Crossref PubMed Scopus (18) Google Scholar37FemaleHard palatePainless and hard mass. Size: 3.0 × 4.0 cmPatchy areas of radiopacity (occlusal radiography)10 yearsMature adipose tissue with scattered trabeculae of lamellar boneHsu et al.15Hsu H.H. Lee L.Y. Chang K.P. Pathology quiz case 2. Osteolipoma of the buccal space.Arch Otolaryngol Head Neck Surg. 2012; 138: 97-98Crossref PubMed Scopus (7) Google Scholar71MaleBuccal mucosaPainless and hard mass. Size: 4.0 × 2.5 cmNA4 yearsLobules of mature adipose tissue separated by fibrous septaRandomly distributed trabeculae of mature lamellar bone and foci of woven boneBajpai et al.16Bajpai M. Kumar M. Agarwal D. Agrawal S. Gupta S. Osteolipoma of the palate—an unusual presentation.Natl J Maxillofac Surg. 2014; 5: 250-251Crossref PubMed Google Scholar55MaleHard palatePainless and hard yellowish mass Size: 1.5 × 1.4 cmPatchy area of radiopacity (occlusal radiography)4 yearsBone trabeculae surrounded by lobules of mature adipocytes separated by fibrous septaAmaral et al.10Amaral M.B. Borges C.F. de Freitas J.B. Capistrano H.M. Mesquita R.A. Osteolipoma of the oral cavity: a case report.J Maxillofac Oral Surg. 2015; 14: 195-199Crossref PubMed Scopus (10) Google Scholar51MaleMandibular buccal mucosaSlight facial asymmetry. Painless and hard mass. Size: 2.0 × 1.5 cmWell-defined hyperechogenic mass with areas of calcification (ultrasonography)3 yearsProliferation of mature fat cells with central areas of lamellar bone trabeculae and fibrous septaRaghunath and Manjunatha17Raghunath V. Manjunatha B.S. Osteolipoma of floor of the mouth.BMJ Case Rep. 2015; 2015 (pii: bcr2015209883)PubMed Google Scholar20FemaleFloor of the mouthPainless and hard yellowish mass Size: 6.0 × 6.0 cmWell-defined, hypodense lesion with irregular hyperdense areas (computed tomography)3 yearsCentral areas of osseous trabeculae and lobules of matured adipose tissueOmonte et al. (current case)29FemaleBuccal mucosaPainless and hard mass. Size: 1.5 × 1.5 cmSpherical radiopacity with an irregular trabecular pattern (radiography)8 monthsMature adipose tissue with fibrous septa and irregular trabeculae of immature boneTumor surrounded by a thin osseous layer and a fibrous capsuleNA, not available. Open table in a new tab NA, not available. Although oral lipomas are believed to be more common in men,3Furlong M.A. Fanburg-Smith J.C. Childers E.L. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004; 98: 441-450Abstract Full Text Full Text PDF PubMed Scopus (223) Google Scholar no clear gender preponderance has been observed in patients with osteolipomas of the oral cavity (see Table I), except for one case of a young boy with an osteolipoma in the palate, most patients affected by oral osteolipoma were adults. Most cases were reported in patients over 40 years of age. A long history of slow progression is commonly observed, although our patient had the lesion for only 8 months. As evident in Table I, osteolipomas of the oral cavity can occur in various anatomic sites, regardless of the proximity to bone. Four cases occurred in the buccal mucosa, four in the mandibular buccal mucosa (vestibule or alveolar mucosa), three in the hard palate, two in the floor of the mouth, and one in the lateral tongue. In the cases of tongue osteolipoma, osteocartilaginous choristoma, osteosarcoma, liposarcoma with metaplasia, and post-traumatic chondrification had been considered in the differential diagnosis.9Piattelli A. Fioroni M. Iezzi G. Rubini C. Osteolipoma of the tongue.Oral Oncol. 2001; 37: 468-470Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar In one case involving the alveolar mucosa, exostosis, peripheral giant cell granuloma, fibrous hyperplasia, and fibroma with calcifications had been considered5Saghafi S. Mellati E. Sohrabi M. Raahpeyma A. Salehinejad J. Zare-Mahmoodabadi R. Osteolipoma of the oral and pharyngeal region: report of a case and review of the literature.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008; 105: e30-e34Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar; and in a case of a palatal osteolipoma, the differential diagnosis had included osteoma, neurofibroma, and intraosseous palatal cyst.6Adebiyi K.E. Ugboko V.I. Maaji S.M. Ndubuizu G. Osteolipoma of the palate: report of a case and review of the literature.Niger J Clin Pract. 2011; 14: 242-244Crossref PubMed Scopus (18) Google Scholar Additionally, with regard to the differential diagnosis, in osteolipomas exhibiting radiographic features, such as the present case, the clinician should consider oral osseous choristoma (soft tissue osteoma), cartilaginous choristoma, chrondrolipoma, pleomorphic adenoma with ossification, and other salivary gland or connective tissue tumors with dystrophic calcification. Suggestive clinical and radiographic features (hard or soft peripheral mass generally associated with a radiopaque area), as well as the histopathologic appearance of mature fatty tissue with diffuse bone trabeculae, usually confirm the diagnosis of osteolipoma (Table I). However, these features are also found in oral osseous choristoma. The term oral osseous choristoma was coined by Krolls et al.18Krolls S.O. Jacoway J.R. Alexander W.N. Osseous choristomas (osteomas) of intraoral soft tissues.Oral Surg Oral Med Oral Pathol. 1971; 32: 588-595Abstract Full Text PDF PubMed Scopus (94) Google Scholar in 1971 to describe benign bone formations in oral soft tissue, previously referred to as soft tissue osteomas. Although oral osseous choristoma generally exhibit a mass of dense lamellar bone,19Chou L.S. Hansen L.S. Daniels T.E. Choristomas of the oral cavity: a review.Oral Surg Oral Med Oral Pathol. 1991; 72: 584-593Abstract Full Text PDF PubMed Scopus (125) Google Scholar which is easily differentiated from an osteolipoma, some of these lesions can display a cancellous pattern. These osseous choristomas, such as the case described by Hodder and MacDonald20Hodder S.C. MacDonald D.G. Osseous choristoma of buccal mucosa: report of a case.Br J Oral Maxillofac Surg. 1988; 26: 78-80Abstract Full Text PDF PubMed Scopus (10) Google Scholar in 1988, display spongy bone trabeculae containing abundant bone marrow spaces filled with fatty tissue, a histologic organization suggestive of that found in osteolipoma. Generally, foci of hemopoietic marrow are encountered in osseous choristomas20Hodder S.C. MacDonald D.G. Osseous choristoma of buccal mucosa: report of a case.Br J Oral Maxillofac Surg. 1988; 26: 78-80Abstract Full Text PDF PubMed Scopus (10) Google Scholar but not in osteolipomas.4Obermann E.C. Bele S. Brawanski A. Knuechel R. Hofstaedter F. Ossifying lipoma.Virchows Arch. 1999; 434: 181-183Crossref PubMed Scopus (44) Google Scholar Hence, this characteristic may be important in the differential diagnosis. Both lesions are benign connective tissue lesions, which are treated by conservative surgical excision and exhibit similar prognoses. The pathogenesis of osteolipomas has not yet been clarified. Some authors have suggested that osteolipomas may originate from two types of undifferentiated mesenchymal cells that separately form adipose and bone cells.21Weiss S.W. Goldblum J.R. Benign lipomatous tumors.in: Enzinger F.M. Weiss S.W. Enzinger and Weiss's Soft Tissue Tumors. 4th ed. Mosby, St. Louis, MO2001: 574-581Google Scholar An alternate theory proposes that multipotent adipose-derived stem cells within adipose tissue may be involved in osteolipoma development. Thus, bone tissue develops inside a lipoma in response to growth signals.22Makiguchi T. Terashi H. Hashikawa K. Yokoo S. Kusaka J. Osteolipoma in the glabella: pathogenesis associated with mesenchymal lipoma-derived stem cells.J Craniofac Surg. 2013; 24: 1310-1313Crossref PubMed Scopus (10) Google Scholar This theory hinges on the assumption that adipose-derived stem cells have the potential to differentiate into fat, bone, cartilage, and vascular components.23Zuk P.A. Zhu M. Mizuno H. et al.Multilineage cells from human adipose tissue: implications for cell-based therapies.Tissue Eng. 2001; 7: 211-228Crossref PubMed Scopus (6393) Google Scholar Some other authors have suggested that repetitive trauma, metabolic changes, or ischemia may lead to metaplasia of pre-existing fibrous elements within lipomas, which then develop into osteoblasts.24Katzer B. Histopathology of rare chondroosteoblastic metaplasia in benign lipomas.Pathol Res Pract. 1989; 184: 437-445Crossref PubMed Scopus (51) Google Scholar, 25Ohno Y. Muraoka M. Ohashi Y. Nakai Y. Wakasa K. Osteolipoma in the parapharyngeal space.Eur Arch Otorhinolaryngol. 1998; 255: 315-317Crossref PubMed Scopus (36) Google Scholar The conditions that induce the differentiation of mesenchymal stem cells into bone remain to be investigated. Although osteolipoma is a very rare entity in the oral cavity, it should be considered when a patient presents with a peripheral lesion that has a hard consistency on palpation, areas of radiopacity in image examinations of peripheral lesions, and mature adipose tissue associated with bone trabeculae in histopathology. It has the same prognosis as a simple lipoma, and surgical excision is the recommended treatment. Recurrences have not been reported.
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