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Parosteal lipoma of the mandible
Parosteal lipoma of the mandible Martin Steiner, D.D.S., * Alan R. Gould, D.D.S., MS., ** James Rasmussen, D.M.D., *** and Daniel LaBriola, D.D.S.,**** Louisville, Ky. UNIVERSITY
OF LOUISVILLE
SCHOOL OF DENTISTRY
The parosteal lipoma represents an uncommon benign neoplasm which usually affects the long bones. An example of parosteal lipoma involving the body of the mandible, which was incidentally discovered on roentgenographic examination, is described. This represents the first reported example affecting the jaws. Benign lipomatous involvement of bone is also reviewed.
occurring in the soft parts constitute one of Lthe ipomas more commonly encounteredtypes of benign neoplasm. Within the oral cavity, the lipoma is distinctly rarer, representing about 1 per cent of all benign oral tumors in the Armed Forces Institute of Pathology files.’ Though generally limited to the soft tissues, a significant number of lipomas affecting bone have been reported,* with three forms being specifically defined.3 These are (1) the intraosseouslipoma, arising within the medullary cavity of the bone and expanding from within, (2) the parosteal lipoma, which exhibits a contiguous relationship with the periosteum, usually demonstrating someform of attachmentto periosteum with an underlying osseousreaction, and (3) the soft-tissue lipoma which, though it may mimic the parosteal lipoma when it occurs near a bone, only secondarily involves the bone by pressureor direct invasion. The intraosseouslipoma is a very rare tumor. Hart* reviewed the world literature in 1973 and reported 28 cases; DeLee,3 in 1979, added five additional cases. The sites of involvement included the long bones (50 per cent), along with the calcaneus,ribs, distal phalanx of the thumb, frontal, parietal, and sacral bones, as well as four tumors in the jaws. Of this latter group, three were found in the mandible4-6 and one in the maxilla.’ A further search of the literature revealed three additional casesaffecting the maxilla.s-10 The parosteal lipoma appearssomewhatmore common than its intraosseouscounterpart, with more than 100casesdocumentedin the world literature. A variety of bones reportedly have been involved, including the *Associate Professor;Departmentof Oral and Maxillofacial Surgery. **Assistant Professor,Department of Oral Pathology/Pathology. ***Senior Resident, Departmentof Oral and MaxiIlofacial Surgery. ****Former Senior Resident, Department of Oral and Maxillofacial Surgery. 0030-4220/81/070061+05$00.50/0
@J 1981
The C. V. Mosby Co.
Fig. 1. Segment of Panorex roentgenogram demonstrating a well-defined radiolucency in the posterior right mandible involving the crestal bone of the body and anterior ramus.
long bones, ribs, skull, scapula, metatarsal, metacarpal, vertebral column, clavicle, and pelvis.” No cases of parosteal lipoma of the mandible or maxilla have been reported as such in the literature, although examples of lipoma have beendescribedin close association with the oral osseous structures occurring in gingiva1*-16and hard palatal mucosa.17-1g Clinically, the parosteallipoma generally presentsas a slowly enlarging but otherwise asymptomatic mass. However, compressionof adjacent structures, such as nerves, has been reported, resulting in functional deficits.*O-*I Fleming, Alpert, and Garcia,” in their review of parosteal lipoma, outlined the roentgenographic and surgical characteristicsof this lesion. The roentgenographic appearance is that of an encapsulated, smooth-surfaced,soft-tissue mass which lies in close relationship to an adjacent bone. Underlying osseouscortical responsesvary, ranging from a reactive overproduction of bone to cortical erosion. Osseous bowing has also been reported as a responseof bone to 61
62
Steiner et al.
Oral surg. July,
1981
Fig. 2. Photomicrographof parosteallipoma demonstratinglobules of adiposetissue with delicate fibrous connective tissue septa. (Hematoxylin and eosin stain. Original magnification, x2.5.)
the overlying parosteal lipoma. The surgical finding is
that of an encapsulated, sometimes bosselated, welldefined, yellow masswhich demonstratesa broad base of attachmentto the periosteumof the underlying bone. Removal of the lesion generally entailed sharp dissection from the periosteum with curettes, leaving behind seemingly thickened periosteum. However, in a significant minority of cases,the lesion displayed little or no attachment to the underlying periosteum. Occasionally the lipoma was associatedwith proliferation of bone arising from the underlying cortex. In these instances, the use of chisels was required to free the mass. The light microscopic features of the parosteal lipoma have, in general, been similar to those of its soft-tissue counterpart, consisting of lobules of mature lipocytes with either prominent or minimal amounts of interlobular fibrous connective tissue.“, 21--25 A fibrous capsulehas been describedrelative to this lesion22and, in distinction to the soft-tissuelipoma, occasionalclose association between benign neoplastic adipose tissue and maturetrabeculaeof bone derived from an underlying hyperostotic responsehas beennoted.22*24Reactive bone has also been described in association with
parosteal lipoma. l1 Recently, a patient presentedto the Oral and Maxillofacial Surgery Outpatient Clinic of the Louisville General Hospital for treatment of a mandibular fracture. During evaluation and examination of this patient, a lesion was encounteredin the right posterior mandible, and the clinical, roentgenographic, surgical, and histologic findings, when taken together, strongly sug-
gested the diagnosis of parosteal lipoma. Given the interest in this case, its unusual roentgenographic features, and the fact that parosteal lipoma has not previously been reported in the jaws, it was felt desirable to report this case. CASE REPORT
A 50-year-old black man presentedto the Oral and Maxillofacial Surgery Outpatient Clinic of Louisville General Hospital on May 3 1, 1979, with a chief complaint of pain and swelling of the anterior part of the mandible. The patient statedthat he had been involved in a motor vehicle accident 4 weeks previously, striking his chin on the dashboard. The patient received no other bodily injury, did not suffer loss of consciousness,and did not seek immediate treatment at the time of the accident. During the subsequent3 weeks, the patient noticed external swelling at the left parasymphysisarea associatedwith drainageof a foul-smelling material intraorally and a marked increasein pain. Pastmedical history revealedthat the patient was a chronic alcohol abuserand had previously been treated for hypertension with Esidrix and Aldomet. The blood pressureon admission was 180/120 mm Hg . The remainderof the physical examination, except for a mandibular fracture, was essentially within normal limits. The patient was placedon Oretec, (50 mg. twice a day), which resulted in a blood pressureof 12OBO.He was subsequentlyto be followed by the General Medical Clinic after discharge from the hospital. Clinical examination of the oral cavity revealed severe periodontal diseaseinvolving the remaining dentition with an obvious fracture of the mandible betweenthe left canine and lateral incisor. There was purulent drainage at this site. Moderate induration was detectedin the submentalarea with
Volume 52 Number 1
Parosteal lipoma of the mandible
63
Fig. 3. Photomicrograph of parosteal lipoma demonstrating mature lipocytes with peripherally displaced flattened nuclei and minimal cytoplasmic contents. (Hematoxylin and eosin stain. Original magnification, X 100.)
Fig. 4. Photomicrograph of parosteal lipoma showing fibrous connective tissue capsule. (Hematoxylin and eosin stain. Original magnification, X25.)
associated lymphadenopathy. The maxilla was intact and the clinical appearance of the intraoral soft tissues was otherwise unremarkable. Roentgenographic examination revealed a left parasymphysis fracture. An incidental roentgenographic finding was a 2.0 by 1.5 cm. well-circumscribed, somewhat cystic-appearing radiolucent lesion of the posterior right mandible (Fig. 1). The lesion extended from the mandibular crest and anterior ramus down into the mandible, presenting a scooped-out appearance. On its inferior and distal aspects, the radiolucency
was bordered by a smooth, sclerotic bony margin. This margin appeared to be continuous distally with the anterior cortex of the mandibular ramus. The lesion was closely associated anteriorly with the distal root of the erupted third molar. No cortical margin of bone was roentgenographically evident overlying the radiolucency. Clinical re-examination of the mandibular right third molar region failed to reveal any expansion. The surrounding gingival tissue was normal in color and texture, and there was no increase in mobility of the third molar. The patient was unaware of the presence of the lesion.
64 Steiner et al. With a provisional diagnosis of odontogenic cyst, the patient was taken to the operating room on June 5, 1979, and general anesthesiawas induced through a nasotrachealtube. With the patient preparedand drapedin the usual manner, the mandibular right second and third molars were removed by means of simple forceps technique. A periosteal flap was raised, and it was noticed that there was a 1.5 cm. masslying within a bony crypt distal to, but associatedwith, the extraction socketof the third molar. The tumor was adherentto the overlying mucosal flap and was curetted from the adjacent tissue with some difficulty. The mass appearedto shell out easily from the bony cavity and was not adherentto the underlying periosteum,leaving a smoothbony cavity. The areawas irrigated and the soft tissue flap was closed with 3-O Dexon sutures. Arch bars were then placed on the remaining maxillary and mandibular teeth for the treatmentof the mandibular fracture. The patient was placed in intermaxillary fixation and taken to the recovery room. Microscopic findings
Histologic examination revealed sections of tissue which were composedof a benign proliferation of adiposetissue in association with dense fibrous connective tissue and viable woven bone. The adipose tissue was arranged in several lobules, separatedby delicate septaof fibrous connective tissue (Fig. 2). These connective tissue septawere composedof coarsecollagenous bundles with fibrocytes, fibroblasts, and endothelium-lined vascular structures filled with red blood cells. The adipose tissue was composedof mature lipocytes exhibiting peripherally displaced, flattened nuclei with little if any cytoplasmic elements(Fig. 3). About the periphery of the tissue was a well-formed fibrous connective tissue capsule (Fig. 4). Portions of this capsular tissue were found in association with trabeculaeof woven bone. The capsulesupported a patchy, dense, chronic inflammatory cell infiltrate of Iymphocytes, macrophages,and occasional polymorphonuclear leukocytes. Several small blood vessels exhibited extensive intimal thickening. The histologic findings, when combined with the clinical and roentgenographicfeatures, were consistent with the diagnosis of parosteallipoma. DISCUSSION This case represents the first reported example of intraoral parosteal lipoma. In analyzing the case, it is useful to make comparisons with previously reported examples affecting extraoral sites. Fleming, Alpert, and Garcia” have summarized the features which characterize the parosteal lipoma. In their series sixteen cases displayed a firm attachment to bone at surgery, four were loosely adherent, three had loose and firm attachment, and two had no attachment to bone. Our case did not exhibit any adherence to the underlying bone or periosteum. In their review” it was found that sixteen of twenty-seven cases had associated bony alterations on roentgenographic examination, with eleven cases specifically exhibiting a hyperostotic reaction. Our case showed a marked radiolucent depression ex-
oral Slug. July, 1981
tending into the crestal bone of the mandible with a very well-defined hyperostotic response. Our patient had no symptoms, and a similar absence of symptoms was noted in ten of twenty-nine cases previously reviewed.” Bick2” has also discussed this lesion, including as characteristic features the creation of a flattened depression in the underlying bony cortex without any evidence of frank invasion. Though a deformation is produced in the surface of the bone, the cortex remains intact. Our case exhibited similar features. The histologic features in the present case embody elements similar to those previously reported for the parosteal lipoma. In addition to the presence of mature adipose tissue and fibrous connective tissue septa, the identification of a fibrous capsule and the association with reactive bone comprise previously reported features for this lesion. l*, 22 A limited number of intraoral lipomas have been described affecting soft tissues directly adjacent to bone. Specific sites involved were the gingiva12-‘” and hard palatal mucosa. Ii-l9 In all of these cases, the lesion clinically presented as a soft tissue mass. Further, in nearly every instance no alterations in the underlying bony structures were described. The single exception to this latter statement is the report of Christensen,15 in which a slight amount of resorption was noted in the maxilla beneath the overlying soft tissue mass. However, the presence of an ill-fitting denture over the mass might well have contributed to the underlying mild resorption. In the present case, no clinical soft-tissue mass was detectable preoperatively; nor were there any associated symptoms. The roentgenographic alterations in the mandible comprised the sole basis for the lesion’s detection, and the preoperative diagnosis was based upon the assumption that the lesion was essentially intraosseous. The surgical findings, however, suggested that the lesion arose in close relationship with the mandibular periosteum and that its growth pattern was such as to create a depression in the bone rather than expanding outward into the soft tissue. The underlying cortical hyperostotic response reflected this pattern of lesional expansion. The clinical and surgical features in the present case are considered sufficiently distinctive to separate the case from examples of extraosseous, intraoral lipoma previously reported in close association with the surface of a bone. Further, our case shares a number of features with the parosteal lipoma as reported in extraoral sites. It is therefore concluded that the present case represents an example of an intraoral parosteal lipoma . REFERENCES 1. Bemier, J. L.: The Management of Oral Disease, ed. 2, St. Louis, 1959, The C. V. Mosby Company, p. 779.
Purosteal lipoma of the mandible
Volume 52 Number 1 2. Hart, J. A. L.: Intraosseous Lipoma, J. Bone Joint Surg. 55-B: 624-632, 1973. 3. DeLee, J C : Intra-Osseous Lipoma of the Proximal Part of the Femur, J. Bone Joint Surg. 61-A: 601-603, 1979. 4. Oringer, M. J.: Lipoma of the Mandible, ORAL SURG. 1: 1134, 1948. 5. Johnson, C. E.: lntraosseous Lipoma, J. Oral Surg. 27: 868870, 1969. 6. Newman, C. W.: Fibrolipomaof the Mandible, J. Oral Surg. 15: 251-252, 1957. I. Salzer, M., and Salzer-Kuntschik, M.: Zur Frage sogenannten zentralen Knochenlipome, Beitr. Pathol. Anat. Allg. Pathol. 132: 365-375, 1965. 8. Lawson, H. P.: Lipoma of the Maxillary Antrum, J. Laryngol. Otol. 57: 382-384, 1942. 9. Goldstein, M. A.: Lipoma of the Maxillary Antrum, Laryngoscope 25: 142-144, 1915. 10. Silbemagel, C. E.: Lipoma of the Maxillary Antrum, Laryngoscope 48: 427-428, 1938. 11. Fleming, R. J., Alpert, M., and Garcia, A.: Parosteal Lipoma, Am. J. Roentgenol. 87: 1075-1084, 1962. 12. Radford, D. L. G.: Fibro-Lipoma in the Mouth, Br. Dent. J. 42: 1092-1093,
ORAL SURG. 12: 489-492,
18. Stewart, S., Levy, R., and Stoopack, J. C.: Fibrolipoma of the Palate, N. Y. State Dent. J. 40: 603-606, 1974. 19. Samuels, H., and Oatis, G. W.: Lipoma of the Hard Palate, ORAL SURG. 28: 134-136,
1959.
14. Bruce, K. W., and Royer, R. Q.: Lipoma of the Oral Cavity, ORAL SURG. 7: 930-938, 1954. 15. Christensen, R. 0.: Surgical Removal of a Fibroma and Lipoma
from the Maxilla, J. Am. Dent. Assoc. 39: 232-233, 1949. 16. Gray, W.: Oral Lipoma, Br. Dent. J. 110: 55-56, 1961. 17. Cran, J. A.: Lipoma of the Palate, ORAL SURG. 16: 452-453, 1963.
1969.
20. Beny, J. B., and Moiel, R. H.: Parosteal Lipoma Producing Paralysis of the Deep Radial Nerve, South. Med. 3. 66: 12981300, 1973. 21. Schweitzer, G.: Parosteal Lipoma of the Radius, S. Afr. Med. J. 44: 648-649, 1970. 22. Khan, A. A., Khan, A. A., and Mathew, B.: Parosteal Lipoma, J. Indian Med. Assoc. 63: 285-286, 1974. 23. Bartlett, E. I.: Periosteal Lipoma-Report of Two Cases, Arch. Surg. 21: 1015-1022, 1930. 24. Kenin, A., Levine, J., and Spinner, M.: Parosteal Lipoma-A Report of Two Cases with Associated Bone Changes, J. Bone Joint Surg. 41-A: 1122-1126, 1959. 25. Kurland, K. Z., and Kennard, J. W.: Parosteal Lipoma Arising From the Proximal Radius: A Case Report, Clin. Orthop. 41: 140-144, 1965. 26. Bick, E.: Lipoma of the Extremities, Ann. Surg. 104: 139-143, 1936. Reprinr
1921.
13. Marfino, N. R.: Developing Fibrolipoma of the Free Gingiva,
65
requests IO:
Dr. Martin Steiner Department of Oral and Maxillofacial School of Dentistry University of Louisville Health Sciences Center Louisville, Ky 40292
Surgery
OF LOUISVILLE
SCHOOL OF DENTISTRY
The parosteal lipoma represents an uncommon benign neoplasm which usually affects the long bones. An example of parosteal lipoma involving the body of the mandible, which was incidentally discovered on roentgenographic examination, is described. This represents the first reported example affecting the jaws. Benign lipomatous involvement of bone is also reviewed.
occurring in the soft parts constitute one of Lthe ipomas more commonly encounteredtypes of benign neoplasm. Within the oral cavity, the lipoma is distinctly rarer, representing about 1 per cent of all benign oral tumors in the Armed Forces Institute of Pathology files.’ Though generally limited to the soft tissues, a significant number of lipomas affecting bone have been reported,* with three forms being specifically defined.3 These are (1) the intraosseouslipoma, arising within the medullary cavity of the bone and expanding from within, (2) the parosteal lipoma, which exhibits a contiguous relationship with the periosteum, usually demonstrating someform of attachmentto periosteum with an underlying osseousreaction, and (3) the soft-tissue lipoma which, though it may mimic the parosteal lipoma when it occurs near a bone, only secondarily involves the bone by pressureor direct invasion. The intraosseouslipoma is a very rare tumor. Hart* reviewed the world literature in 1973 and reported 28 cases; DeLee,3 in 1979, added five additional cases. The sites of involvement included the long bones (50 per cent), along with the calcaneus,ribs, distal phalanx of the thumb, frontal, parietal, and sacral bones, as well as four tumors in the jaws. Of this latter group, three were found in the mandible4-6 and one in the maxilla.’ A further search of the literature revealed three additional casesaffecting the maxilla.s-10 The parosteal lipoma appearssomewhatmore common than its intraosseouscounterpart, with more than 100casesdocumentedin the world literature. A variety of bones reportedly have been involved, including the *Associate Professor;Departmentof Oral and Maxillofacial Surgery. **Assistant Professor,Department of Oral Pathology/Pathology. ***Senior Resident, Departmentof Oral and MaxiIlofacial Surgery. ****Former Senior Resident, Department of Oral and Maxillofacial Surgery. 0030-4220/81/070061+05$00.50/0
@J 1981
The C. V. Mosby Co.
Fig. 1. Segment of Panorex roentgenogram demonstrating a well-defined radiolucency in the posterior right mandible involving the crestal bone of the body and anterior ramus.
long bones, ribs, skull, scapula, metatarsal, metacarpal, vertebral column, clavicle, and pelvis.” No cases of parosteal lipoma of the mandible or maxilla have been reported as such in the literature, although examples of lipoma have beendescribedin close association with the oral osseous structures occurring in gingiva1*-16and hard palatal mucosa.17-1g Clinically, the parosteallipoma generally presentsas a slowly enlarging but otherwise asymptomatic mass. However, compressionof adjacent structures, such as nerves, has been reported, resulting in functional deficits.*O-*I Fleming, Alpert, and Garcia,” in their review of parosteal lipoma, outlined the roentgenographic and surgical characteristicsof this lesion. The roentgenographic appearance is that of an encapsulated, smooth-surfaced,soft-tissue mass which lies in close relationship to an adjacent bone. Underlying osseouscortical responsesvary, ranging from a reactive overproduction of bone to cortical erosion. Osseous bowing has also been reported as a responseof bone to 61
62
Steiner et al.
Oral surg. July,
1981
Fig. 2. Photomicrographof parosteallipoma demonstratinglobules of adiposetissue with delicate fibrous connective tissue septa. (Hematoxylin and eosin stain. Original magnification, x2.5.)
the overlying parosteal lipoma. The surgical finding is
that of an encapsulated, sometimes bosselated, welldefined, yellow masswhich demonstratesa broad base of attachmentto the periosteumof the underlying bone. Removal of the lesion generally entailed sharp dissection from the periosteum with curettes, leaving behind seemingly thickened periosteum. However, in a significant minority of cases,the lesion displayed little or no attachment to the underlying periosteum. Occasionally the lipoma was associatedwith proliferation of bone arising from the underlying cortex. In these instances, the use of chisels was required to free the mass. The light microscopic features of the parosteal lipoma have, in general, been similar to those of its soft-tissue counterpart, consisting of lobules of mature lipocytes with either prominent or minimal amounts of interlobular fibrous connective tissue.“, 21--25 A fibrous capsulehas been describedrelative to this lesion22and, in distinction to the soft-tissuelipoma, occasionalclose association between benign neoplastic adipose tissue and maturetrabeculaeof bone derived from an underlying hyperostotic responsehas beennoted.22*24Reactive bone has also been described in association with
parosteal lipoma. l1 Recently, a patient presentedto the Oral and Maxillofacial Surgery Outpatient Clinic of the Louisville General Hospital for treatment of a mandibular fracture. During evaluation and examination of this patient, a lesion was encounteredin the right posterior mandible, and the clinical, roentgenographic, surgical, and histologic findings, when taken together, strongly sug-
gested the diagnosis of parosteal lipoma. Given the interest in this case, its unusual roentgenographic features, and the fact that parosteal lipoma has not previously been reported in the jaws, it was felt desirable to report this case. CASE REPORT
A 50-year-old black man presentedto the Oral and Maxillofacial Surgery Outpatient Clinic of Louisville General Hospital on May 3 1, 1979, with a chief complaint of pain and swelling of the anterior part of the mandible. The patient statedthat he had been involved in a motor vehicle accident 4 weeks previously, striking his chin on the dashboard. The patient received no other bodily injury, did not suffer loss of consciousness,and did not seek immediate treatment at the time of the accident. During the subsequent3 weeks, the patient noticed external swelling at the left parasymphysisarea associatedwith drainageof a foul-smelling material intraorally and a marked increasein pain. Pastmedical history revealedthat the patient was a chronic alcohol abuserand had previously been treated for hypertension with Esidrix and Aldomet. The blood pressureon admission was 180/120 mm Hg . The remainderof the physical examination, except for a mandibular fracture, was essentially within normal limits. The patient was placedon Oretec, (50 mg. twice a day), which resulted in a blood pressureof 12OBO.He was subsequentlyto be followed by the General Medical Clinic after discharge from the hospital. Clinical examination of the oral cavity revealed severe periodontal diseaseinvolving the remaining dentition with an obvious fracture of the mandible betweenthe left canine and lateral incisor. There was purulent drainage at this site. Moderate induration was detectedin the submentalarea with
Volume 52 Number 1
Parosteal lipoma of the mandible
63
Fig. 3. Photomicrograph of parosteal lipoma demonstrating mature lipocytes with peripherally displaced flattened nuclei and minimal cytoplasmic contents. (Hematoxylin and eosin stain. Original magnification, X 100.)
Fig. 4. Photomicrograph of parosteal lipoma showing fibrous connective tissue capsule. (Hematoxylin and eosin stain. Original magnification, X25.)
associated lymphadenopathy. The maxilla was intact and the clinical appearance of the intraoral soft tissues was otherwise unremarkable. Roentgenographic examination revealed a left parasymphysis fracture. An incidental roentgenographic finding was a 2.0 by 1.5 cm. well-circumscribed, somewhat cystic-appearing radiolucent lesion of the posterior right mandible (Fig. 1). The lesion extended from the mandibular crest and anterior ramus down into the mandible, presenting a scooped-out appearance. On its inferior and distal aspects, the radiolucency
was bordered by a smooth, sclerotic bony margin. This margin appeared to be continuous distally with the anterior cortex of the mandibular ramus. The lesion was closely associated anteriorly with the distal root of the erupted third molar. No cortical margin of bone was roentgenographically evident overlying the radiolucency. Clinical re-examination of the mandibular right third molar region failed to reveal any expansion. The surrounding gingival tissue was normal in color and texture, and there was no increase in mobility of the third molar. The patient was unaware of the presence of the lesion.
64 Steiner et al. With a provisional diagnosis of odontogenic cyst, the patient was taken to the operating room on June 5, 1979, and general anesthesiawas induced through a nasotrachealtube. With the patient preparedand drapedin the usual manner, the mandibular right second and third molars were removed by means of simple forceps technique. A periosteal flap was raised, and it was noticed that there was a 1.5 cm. masslying within a bony crypt distal to, but associatedwith, the extraction socketof the third molar. The tumor was adherentto the overlying mucosal flap and was curetted from the adjacent tissue with some difficulty. The mass appearedto shell out easily from the bony cavity and was not adherentto the underlying periosteum,leaving a smoothbony cavity. The areawas irrigated and the soft tissue flap was closed with 3-O Dexon sutures. Arch bars were then placed on the remaining maxillary and mandibular teeth for the treatmentof the mandibular fracture. The patient was placed in intermaxillary fixation and taken to the recovery room. Microscopic findings
Histologic examination revealed sections of tissue which were composedof a benign proliferation of adiposetissue in association with dense fibrous connective tissue and viable woven bone. The adipose tissue was arranged in several lobules, separatedby delicate septaof fibrous connective tissue (Fig. 2). These connective tissue septawere composedof coarsecollagenous bundles with fibrocytes, fibroblasts, and endothelium-lined vascular structures filled with red blood cells. The adipose tissue was composedof mature lipocytes exhibiting peripherally displaced, flattened nuclei with little if any cytoplasmic elements(Fig. 3). About the periphery of the tissue was a well-formed fibrous connective tissue capsule (Fig. 4). Portions of this capsular tissue were found in association with trabeculaeof woven bone. The capsulesupported a patchy, dense, chronic inflammatory cell infiltrate of Iymphocytes, macrophages,and occasional polymorphonuclear leukocytes. Several small blood vessels exhibited extensive intimal thickening. The histologic findings, when combined with the clinical and roentgenographicfeatures, were consistent with the diagnosis of parosteallipoma. DISCUSSION This case represents the first reported example of intraoral parosteal lipoma. In analyzing the case, it is useful to make comparisons with previously reported examples affecting extraoral sites. Fleming, Alpert, and Garcia” have summarized the features which characterize the parosteal lipoma. In their series sixteen cases displayed a firm attachment to bone at surgery, four were loosely adherent, three had loose and firm attachment, and two had no attachment to bone. Our case did not exhibit any adherence to the underlying bone or periosteum. In their review” it was found that sixteen of twenty-seven cases had associated bony alterations on roentgenographic examination, with eleven cases specifically exhibiting a hyperostotic reaction. Our case showed a marked radiolucent depression ex-
oral Slug. July, 1981
tending into the crestal bone of the mandible with a very well-defined hyperostotic response. Our patient had no symptoms, and a similar absence of symptoms was noted in ten of twenty-nine cases previously reviewed.” Bick2” has also discussed this lesion, including as characteristic features the creation of a flattened depression in the underlying bony cortex without any evidence of frank invasion. Though a deformation is produced in the surface of the bone, the cortex remains intact. Our case exhibited similar features. The histologic features in the present case embody elements similar to those previously reported for the parosteal lipoma. In addition to the presence of mature adipose tissue and fibrous connective tissue septa, the identification of a fibrous capsule and the association with reactive bone comprise previously reported features for this lesion. l*, 22 A limited number of intraoral lipomas have been described affecting soft tissues directly adjacent to bone. Specific sites involved were the gingiva12-‘” and hard palatal mucosa. Ii-l9 In all of these cases, the lesion clinically presented as a soft tissue mass. Further, in nearly every instance no alterations in the underlying bony structures were described. The single exception to this latter statement is the report of Christensen,15 in which a slight amount of resorption was noted in the maxilla beneath the overlying soft tissue mass. However, the presence of an ill-fitting denture over the mass might well have contributed to the underlying mild resorption. In the present case, no clinical soft-tissue mass was detectable preoperatively; nor were there any associated symptoms. The roentgenographic alterations in the mandible comprised the sole basis for the lesion’s detection, and the preoperative diagnosis was based upon the assumption that the lesion was essentially intraosseous. The surgical findings, however, suggested that the lesion arose in close relationship with the mandibular periosteum and that its growth pattern was such as to create a depression in the bone rather than expanding outward into the soft tissue. The underlying cortical hyperostotic response reflected this pattern of lesional expansion. The clinical and surgical features in the present case are considered sufficiently distinctive to separate the case from examples of extraosseous, intraoral lipoma previously reported in close association with the surface of a bone. Further, our case shares a number of features with the parosteal lipoma as reported in extraoral sites. It is therefore concluded that the present case represents an example of an intraoral parosteal lipoma . REFERENCES 1. Bemier, J. L.: The Management of Oral Disease, ed. 2, St. Louis, 1959, The C. V. Mosby Company, p. 779.
Purosteal lipoma of the mandible
Volume 52 Number 1 2. Hart, J. A. L.: Intraosseous Lipoma, J. Bone Joint Surg. 55-B: 624-632, 1973. 3. DeLee, J C : Intra-Osseous Lipoma of the Proximal Part of the Femur, J. Bone Joint Surg. 61-A: 601-603, 1979. 4. Oringer, M. J.: Lipoma of the Mandible, ORAL SURG. 1: 1134, 1948. 5. Johnson, C. E.: lntraosseous Lipoma, J. Oral Surg. 27: 868870, 1969. 6. Newman, C. W.: Fibrolipomaof the Mandible, J. Oral Surg. 15: 251-252, 1957. I. Salzer, M., and Salzer-Kuntschik, M.: Zur Frage sogenannten zentralen Knochenlipome, Beitr. Pathol. Anat. Allg. Pathol. 132: 365-375, 1965. 8. Lawson, H. P.: Lipoma of the Maxillary Antrum, J. Laryngol. Otol. 57: 382-384, 1942. 9. Goldstein, M. A.: Lipoma of the Maxillary Antrum, Laryngoscope 25: 142-144, 1915. 10. Silbemagel, C. E.: Lipoma of the Maxillary Antrum, Laryngoscope 48: 427-428, 1938. 11. Fleming, R. J., Alpert, M., and Garcia, A.: Parosteal Lipoma, Am. J. Roentgenol. 87: 1075-1084, 1962. 12. Radford, D. L. G.: Fibro-Lipoma in the Mouth, Br. Dent. J. 42: 1092-1093,
ORAL SURG. 12: 489-492,
18. Stewart, S., Levy, R., and Stoopack, J. C.: Fibrolipoma of the Palate, N. Y. State Dent. J. 40: 603-606, 1974. 19. Samuels, H., and Oatis, G. W.: Lipoma of the Hard Palate, ORAL SURG. 28: 134-136,
1959.
14. Bruce, K. W., and Royer, R. Q.: Lipoma of the Oral Cavity, ORAL SURG. 7: 930-938, 1954. 15. Christensen, R. 0.: Surgical Removal of a Fibroma and Lipoma
from the Maxilla, J. Am. Dent. Assoc. 39: 232-233, 1949. 16. Gray, W.: Oral Lipoma, Br. Dent. J. 110: 55-56, 1961. 17. Cran, J. A.: Lipoma of the Palate, ORAL SURG. 16: 452-453, 1963.
1969.
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requests IO:
Dr. Martin Steiner Department of Oral and Maxillofacial School of Dentistry University of Louisville Health Sciences Center Louisville, Ky 40292
Surgery