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Osteoma in mandibular condyle
Int. J. Oral Maxillofac. Surg. 1987: 16:372-375 (Key words: osteoma; mandible," tumor, osseous; surgery, oral and maxillofacial)
Osteoma in mandibular condyle K A Z U H I S A BESSHO, K E N - I C H I R O M U R A K A M I , T A D A H I K O I I Z U K A A N D TAKATOKI ONO
Department of Oral and Maxillofacial Surgery, Faculty of Medicine, Kyoto University, Kyoto, Japan
ABSTRACT A case of peripheral osteoma occurring in the mandibular ramus in a 26-year-old man is reported. Radiographic examination revealed a pedunculated, protruding globular, bone-like opaque mass around the notch of the right mandibular ramus. Histopathotogical examination showed a lamellar bone structure with irregular arrangement. Wide trabeculae, narrow interstitial areas, and many fibrovascular channels were detected by scanning electron microscopy. Thus, characteristic findings of a compact osteoma were obtained clinically and histopathologically. - -
(Accepted for publication 30 July 1986)
Recently, a p e r i p h e r a l o s t e o m a a p p e a r i n g at the right m a n d i b u l a r n o t c h was e n c o u n ted. A r e p o r t o f a case and a review o f the literature are presented.
Case report A 26-year-old man was referred to the Department of Oral and Maxillo-facial Surgery, Kyoto University Hospital with the complaint of swelling in the right buccal region. The patient had received a blow on the region at 14 years of age, which was followed by gradual painless swelling and bulging sensation of bone. His general condition revealed nothing particular. His face appeared slightly asymmetric due to the mass in the right parotid region. A pigeon egg-sized mass was palpable; it was hard and firmly fixed to the ascending rumus. On radiographic examination, a pedunculated, protruding globular, bone-like opaque mass was found around the outside of the right mandibular notch (Fig. 1). Lateral tomographies revealed a well-defined, opaque mass, which was located ar-
ound the mandibular notch below the mandibular neck. The mandibular head was normal in its shape. Bone scintigraphy with 99~Tc-MDP showed a slight increase of Rl-uptake at the corresponding site (Fig. 2). No abnormalities were found in blood analysis and urinalysis. Thus, a clinical diagnosis of peripheral osteoma in the right mandibular ramus was made. On 22 June 1984, the tumor was resected under general anesthesia. A bone-like mass was observed, protruding spheroidal; it was located posteriorly to the mandibular notch just below the mandibular neck. An attempt to hammer and separate the mass from the mandibular ramus using a bone chisel was unsuccessful. The mass was fnaUy excised as a lump by prying with a bar between the tumor and the mandible. The postoperative course was uneventful. The excised mass was spheroidal, measuring 2.9 x 3.4 x 1.7 cm. The surface was uneven and mulberry-like. The weight was 18.6 g, the volume 9.3 cm 3 and the specific gravity 2.0. When the section was examined, the mass was covered with a thin bony cortex-like structure and showed a bony structure containing few interstitial areas.
OSTEOMA OF CONDYLAR NECK
373
Fig. 2. Bone scintigraphic fnding with 9~mTCMDE Fig. 1. Panorama X-ray findings. Radiographs showing swelling of the osteoma arising from the right ascending ramus of the mandible.
Histopathological examinations were performed on the decalcificated and H.E.-stained specimens. The circumference was mantled in the bone cortex, consisting of 2 layers of trabecula evident and regularly arranged. The inside of the mass was mature, compact bone tissue, in which evident and wide trabeculae were irregularly distributed; osteoblasts were scarcely observed (Fig. 3). Many fibrovascular channels (Fig. 4a) and the formation of a trabecula with a lamellar structure (Fig. 4b) were observed under a scanning electron microscope.
Discussion Various factors have been p r o p o s e d in the etiology o f osteoma, such as congenital and hereditary endocrine disorders, external
stimulation a n d chronic inflammations L3,12. THOMA13 speculated that a t r a u m a rather than inflammations are generally involved in tumorigenesis. The previous history in this patient suggests a similar causative factor. O s t e o m a is frequently confused with exostosis, o s t e o c h o n d o r o m a or hyperostosis, since its histopathological features are not well-defined. However, as stated above TM, clinically it is widely accepted that osteoma is globular a n d pedunculated and occurs singly from u n k n o w n cause. H i s t o p a t h o l o gically, MIYACHI8 found that osteoma consisted o f irregularly distributed, wide trabeculae without active osteoblasts and with intertrabeculae tissue. Scanning electron microscopic observations m a d e by GRAIJA~a4 disclosed the following. The bone is
374
BESSHO, MURAKAMI, IIZUKA AND ONO
Fig. 3. Findings on decalcified histopathological
specimen (H.E.-stain). (a) The circumference of the mass is shown. A bone cortex consisting of 2 layers is evident. (b) The inside of mass showing distinct, wide trabeculae, distributed irregularly.
characterized by an abundance of discrete, fibrovascular channels surrounded by laminated bone. These channels are frequently irregular and contain abundant, fibrous tissue and sinusoidal blood vessels. The appearance o f bone between these lesions varies, but is primarily dense and oriented in multiple directions. Hardly any osteoblasts are found in the inner structure of osteoma. In the present case, the mass was spheroidal and microscopically pedunculated with a size of 2.9 × 3.4 × 1.7 cm, lamellar structure that was evident and arranged irregularly; the trabeculae were wide and the interstitial area was narrow histopathologically, and m a n y irregular fibrovascular channels were abserved under a scanning electron micro-
Fig. 4. Scanning electron microscopic findings.
(a) Many fibrovascular channels are shown irregularly. (b) These channels are surrounded by laminated bone and contain abundant, fibrous tissue and sinusoids.
scope. Thus, a diagnosis o f peripheral osteoma could be made. The mandibular angle is one o f the sites where osteoma occurs frequently 6,1° but a peripheral osteoma occurring near the mandibular notch below the mandibular neck, seems to be rare. SCHNEIDER et al. (1980) 9 reviewed the (English) literature of peripheral osteomas of the jaw, and found only one case occurring in the lateral side o f ascending ramus described by Ggn~N & BOWERMAN5. Another case was reported by LUCAS7. It m a y be considered that the tumor location in the lateral side o f the ascending ramus would be rare, though the first case occurred in the mandibular notch.
OSTEOMA OF CONDYLAR NECK
References 1. BORNHAUPT, T.: Ein Fall von linksseitigem Stirnh6hlen-Osteom. Arch. Klin. Chirurgie. 1881: 26: 589-644. 2. DIBARTOLOMEO,J. R.: Exostosis of the external auditory canal. Ann. Otol. Suppl. 1979: 61: 2-20. 3. PEriSSOF, A. G.: Pathogenesis of osteomas of the nasal accessory sinuses. Ann. Otol. Rhinol. & Laryng. 1929: 38: 404--420. 4. GRAHAM,M. D.: Osteomas and exostosis of the external auditory canal. A clinical, histopathologic and scanning electron microscopic study. Ann. Otol. 1979: 88: 566-572. 5. GREEN, A. E. & BOWERMAN,J. E.: An osteoma of the mandible. Br. J. Oral Surg. 1974: 12: 225-228. 6. KRAGH, L. V.: Bone tumors of the jaws. In: GOUN, R. J. & GOLDMAN, H. M. (ed.): Thoma's oralpathology, 6th edition, vol. 1. C. V. Mosby Co., St. Louis 1970, pp. 560-576. 7. LUCAS,R. B.: Pathology of tumors of the oral tissues, 3rd edition. Churchill Livingstone. Edinburgh 1976, pp. 197-200.
375
8. MIYACHI, T." Clinical histopothology. Kyorin Shoin. Tokyo 1976, p. 706. 9. SCHNEIDER,L. C., DOLINSKY,H. B. & GRODJESK, J. E.: Solitary peripheral osteoma of the jaws. J. Oral Surg. 1980: 38: 452-455. 10. SHAFER,W. G., HIN~, M. K. & LEVY, B. M.: A textbook of oral pathology, 4th edition. W. B. Saunders Co., Philadelphia 1983, pp. 163-164. 11. SI-mEHLY,J. L.: Osteoma of the external auditory canal. Laryngoscope 1958: 68: 1667-1673. 12. STUART,E. A.: Osteoma of the mastoid. Arch. Otolaryngol. 1940: 31: 838-854. 13. THOMA,K. H.: Oralpathology, 4th edition. C. V. Mosby Co., St. Louis 1954, pp. 1251-1259. Address:
Kazuhisa Bessho Department of Oral Surgery Mie University School of Medicine 174 2 chome, Edobashi Tsu Mie 514 Japan
Osteoma in mandibular condyle K A Z U H I S A BESSHO, K E N - I C H I R O M U R A K A M I , T A D A H I K O I I Z U K A A N D TAKATOKI ONO
Department of Oral and Maxillofacial Surgery, Faculty of Medicine, Kyoto University, Kyoto, Japan
ABSTRACT A case of peripheral osteoma occurring in the mandibular ramus in a 26-year-old man is reported. Radiographic examination revealed a pedunculated, protruding globular, bone-like opaque mass around the notch of the right mandibular ramus. Histopathotogical examination showed a lamellar bone structure with irregular arrangement. Wide trabeculae, narrow interstitial areas, and many fibrovascular channels were detected by scanning electron microscopy. Thus, characteristic findings of a compact osteoma were obtained clinically and histopathologically. - -
(Accepted for publication 30 July 1986)
Recently, a p e r i p h e r a l o s t e o m a a p p e a r i n g at the right m a n d i b u l a r n o t c h was e n c o u n ted. A r e p o r t o f a case and a review o f the literature are presented.
Case report A 26-year-old man was referred to the Department of Oral and Maxillo-facial Surgery, Kyoto University Hospital with the complaint of swelling in the right buccal region. The patient had received a blow on the region at 14 years of age, which was followed by gradual painless swelling and bulging sensation of bone. His general condition revealed nothing particular. His face appeared slightly asymmetric due to the mass in the right parotid region. A pigeon egg-sized mass was palpable; it was hard and firmly fixed to the ascending rumus. On radiographic examination, a pedunculated, protruding globular, bone-like opaque mass was found around the outside of the right mandibular notch (Fig. 1). Lateral tomographies revealed a well-defined, opaque mass, which was located ar-
ound the mandibular notch below the mandibular neck. The mandibular head was normal in its shape. Bone scintigraphy with 99~Tc-MDP showed a slight increase of Rl-uptake at the corresponding site (Fig. 2). No abnormalities were found in blood analysis and urinalysis. Thus, a clinical diagnosis of peripheral osteoma in the right mandibular ramus was made. On 22 June 1984, the tumor was resected under general anesthesia. A bone-like mass was observed, protruding spheroidal; it was located posteriorly to the mandibular notch just below the mandibular neck. An attempt to hammer and separate the mass from the mandibular ramus using a bone chisel was unsuccessful. The mass was fnaUy excised as a lump by prying with a bar between the tumor and the mandible. The postoperative course was uneventful. The excised mass was spheroidal, measuring 2.9 x 3.4 x 1.7 cm. The surface was uneven and mulberry-like. The weight was 18.6 g, the volume 9.3 cm 3 and the specific gravity 2.0. When the section was examined, the mass was covered with a thin bony cortex-like structure and showed a bony structure containing few interstitial areas.
OSTEOMA OF CONDYLAR NECK
373
Fig. 2. Bone scintigraphic fnding with 9~mTCMDE Fig. 1. Panorama X-ray findings. Radiographs showing swelling of the osteoma arising from the right ascending ramus of the mandible.
Histopathological examinations were performed on the decalcificated and H.E.-stained specimens. The circumference was mantled in the bone cortex, consisting of 2 layers of trabecula evident and regularly arranged. The inside of the mass was mature, compact bone tissue, in which evident and wide trabeculae were irregularly distributed; osteoblasts were scarcely observed (Fig. 3). Many fibrovascular channels (Fig. 4a) and the formation of a trabecula with a lamellar structure (Fig. 4b) were observed under a scanning electron microscope.
Discussion Various factors have been p r o p o s e d in the etiology o f osteoma, such as congenital and hereditary endocrine disorders, external
stimulation a n d chronic inflammations L3,12. THOMA13 speculated that a t r a u m a rather than inflammations are generally involved in tumorigenesis. The previous history in this patient suggests a similar causative factor. O s t e o m a is frequently confused with exostosis, o s t e o c h o n d o r o m a or hyperostosis, since its histopathological features are not well-defined. However, as stated above TM, clinically it is widely accepted that osteoma is globular a n d pedunculated and occurs singly from u n k n o w n cause. H i s t o p a t h o l o gically, MIYACHI8 found that osteoma consisted o f irregularly distributed, wide trabeculae without active osteoblasts and with intertrabeculae tissue. Scanning electron microscopic observations m a d e by GRAIJA~a4 disclosed the following. The bone is
374
BESSHO, MURAKAMI, IIZUKA AND ONO
Fig. 3. Findings on decalcified histopathological
specimen (H.E.-stain). (a) The circumference of the mass is shown. A bone cortex consisting of 2 layers is evident. (b) The inside of mass showing distinct, wide trabeculae, distributed irregularly.
characterized by an abundance of discrete, fibrovascular channels surrounded by laminated bone. These channels are frequently irregular and contain abundant, fibrous tissue and sinusoidal blood vessels. The appearance o f bone between these lesions varies, but is primarily dense and oriented in multiple directions. Hardly any osteoblasts are found in the inner structure of osteoma. In the present case, the mass was spheroidal and microscopically pedunculated with a size of 2.9 × 3.4 × 1.7 cm, lamellar structure that was evident and arranged irregularly; the trabeculae were wide and the interstitial area was narrow histopathologically, and m a n y irregular fibrovascular channels were abserved under a scanning electron micro-
Fig. 4. Scanning electron microscopic findings.
(a) Many fibrovascular channels are shown irregularly. (b) These channels are surrounded by laminated bone and contain abundant, fibrous tissue and sinusoids.
scope. Thus, a diagnosis o f peripheral osteoma could be made. The mandibular angle is one o f the sites where osteoma occurs frequently 6,1° but a peripheral osteoma occurring near the mandibular notch below the mandibular neck, seems to be rare. SCHNEIDER et al. (1980) 9 reviewed the (English) literature of peripheral osteomas of the jaw, and found only one case occurring in the lateral side o f ascending ramus described by Ggn~N & BOWERMAN5. Another case was reported by LUCAS7. It m a y be considered that the tumor location in the lateral side o f the ascending ramus would be rare, though the first case occurred in the mandibular notch.
OSTEOMA OF CONDYLAR NECK
References 1. BORNHAUPT, T.: Ein Fall von linksseitigem Stirnh6hlen-Osteom. Arch. Klin. Chirurgie. 1881: 26: 589-644. 2. DIBARTOLOMEO,J. R.: Exostosis of the external auditory canal. Ann. Otol. Suppl. 1979: 61: 2-20. 3. PEriSSOF, A. G.: Pathogenesis of osteomas of the nasal accessory sinuses. Ann. Otol. Rhinol. & Laryng. 1929: 38: 404--420. 4. GRAHAM,M. D.: Osteomas and exostosis of the external auditory canal. A clinical, histopathologic and scanning electron microscopic study. Ann. Otol. 1979: 88: 566-572. 5. GREEN, A. E. & BOWERMAN,J. E.: An osteoma of the mandible. Br. J. Oral Surg. 1974: 12: 225-228. 6. KRAGH, L. V.: Bone tumors of the jaws. In: GOUN, R. J. & GOLDMAN, H. M. (ed.): Thoma's oralpathology, 6th edition, vol. 1. C. V. Mosby Co., St. Louis 1970, pp. 560-576. 7. LUCAS,R. B.: Pathology of tumors of the oral tissues, 3rd edition. Churchill Livingstone. Edinburgh 1976, pp. 197-200.
375
8. MIYACHI, T." Clinical histopothology. Kyorin Shoin. Tokyo 1976, p. 706. 9. SCHNEIDER,L. C., DOLINSKY,H. B. & GRODJESK, J. E.: Solitary peripheral osteoma of the jaws. J. Oral Surg. 1980: 38: 452-455. 10. SHAFER,W. G., HIN~, M. K. & LEVY, B. M.: A textbook of oral pathology, 4th edition. W. B. Saunders Co., Philadelphia 1983, pp. 163-164. 11. SI-mEHLY,J. L.: Osteoma of the external auditory canal. Laryngoscope 1958: 68: 1667-1673. 12. STUART,E. A.: Osteoma of the mastoid. Arch. Otolaryngol. 1940: 31: 838-854. 13. THOMA,K. H.: Oralpathology, 4th edition. C. V. Mosby Co., St. Louis 1954, pp. 1251-1259. Address:
Kazuhisa Bessho Department of Oral Surgery Mie University School of Medicine 174 2 chome, Edobashi Tsu Mie 514 Japan