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Large exostosis of the mandibular coronoid process
Large exostosis of the mandibular process
coronoid
Report of a case Souichiro Asanami, DDS, PhD,a and Yasunori Kasazaki, DDS,a and Ikuhiro Uchida, DDS,b Tokyo, Japan KEIO
UNIVERSITY
AND
TOKYO
METROPOLITAN
KOMAGOME
HOSPITAL
The clinical experience of a patient with a large exostosis who had a chief complaint of difficulty in opening the mouth is reported. Radiographic examinations, especially tomography and a CT scan, were useful in the diagnosis. Surgical removal is the treatment of choice. The lesion is usually approached by a combination of intraoral and buccal routes; we also employed such an approach in this particular case. (ORAL SURC ORAL MED ORAL PATHOL
1990;69:559-62)
P
atients with an oral disease often come to us with complaints of difficulty in opening the mouth; however, this trouble rarely results from disorders of the coronoid process. We herein report our experience with a patient who had a diagnosis of exostosis of the coronoid process whose chief complaint was severe difficulty in opening the mouth. CASE REPORT
A 17-year-old male patient came to our department with a chief complaint of difficulty in opening his mouth. Patient and family histories were noncontributory. The history of the present illness went back to the age of 13 years, when the patient had a slight opening difficulty, joint grating, and a prominence of the left cheek, but his condition was initially left untreated. After that, a diagnosis of temporomandibular arthrosis was reached and a bite splint was placed in his mouth at a hospital; however, no improvement was observed. In May 1982, therefore, he visited a university hospital and was told, on the basis of radiographic examinations, that he had an enlarged left mandibular coronoid process.After that, progression of his difficulty in opening the mouth and a gradual enlargement of the prominence of the left cheek brought him to our department in April 1984. Physical examination determined that he was well developedand well nourished. Chest radiographs and EKG were normal. Laboratory data were within normal limits aDepartment of Dentistry and Oral Surgery, School of Medicine, Keio University, Tokyo, Japan. bDepartment of Oral Surgery, Tokyo Metropolitan Komagome Hospital.
7/12/11391
except for an elevated creatine phosphokinase level. The face was asymmetric because of a bony mass protruding into the left cheek. The skin covering it remained normal in color, without any tenderness or fever. The maximum distance of opening of the mouth was 8 mm. The central line of the mandible was slightly deviated to the left (Fig. 1). At the time of jaw movement, the right mandibular head moved anteriorly without any audible crepitation or grating; however, the left one did not move. The bilateral submandibular lymph nodes were not palpable. Radiographic jindings. Tomography revealed a welldemarcated radiopaque bony shadow extending continuously both anterosuperiorly and laterally from the left mandibular coronoid process (Fig. 2). An occipitomental film and cranial CT scan showed that the radiopaque shadow originated in the coronoid process,extended with a thick pedicle, and ended with a mushroom-shaped apex, and that the zygomatic bone, compressed by the lesion, protruded laterally (Fig. 3). With a tentative diagnosis of an enlarged left mandibular coronoid process,surgery was undertaken, with the patient under general anesthesia, in August 1984. The lesion was approached from both the inside and outside of the oral cavity. Incision was made continuously from the gingivobuccal transition at the maxillary molar area to the anterior ramus of the mandibule. The mucoperiosteal flap was bluntly dissected. Then, the coronoid process was exposed. It was amputated at its base to enable him to open his mouth. A transverse incision was made on the skin over the zygomatic bone, which was then opened to remove the mass.The tissue swelling disappeared 7 days after surgery, and the mouth-opening distance improved to 25 mm. It became 37 mm 1 month after surgery and 48 mm 2 months after surgery (Fig. 4). By that time, he did not have any difficulty in jaw movement or facial nerve palsy. The mouth-opening distance became 64 mm 559
560
Asanami, Kasazaki, and Uchida
ORAL SURG ORAL MED ORAL PATHOL May 1990
Fig.
Fig.
1. Maximum opening at first visit.
3. Cranial CT scan on first visit.
without any jaw deviation within 3 years (in August 1987). A radiograph demonstrated that the left mandibular coronoid processwas defective and that the mandibular ramus below the area seemedto have a thicker cortical bone than the opposite side (Fig. 5). The mass removed was measured as 51 X 45 X 25 mm, and its tip, protruding like a bow from the coronoid process,consisted mostly of a bony core in addition to a rim of a chondroid structure (Fig. 6). Histopathologic findings revealed that the protruded mass was mainly composedof newly developed bony trabeculae, whereas its bone marrow was identified as a fatty marrow. As for the connective tissue surrounding the lesion, all the layers were observed to be similar, though irregularly, to the normal epiphyseal growth. In the outer layer of the cartilage cap, slightly immature fibrous mesenchymal cells were also observed. The histopathologic diagnosis of osteocartilaginous exostosis was, therefore, established (Fig. 7). DISCUSSION
Histologic classifications of bone tumors differ depending on the sites involved, and the nomenclature used is not always consistent. There is thus some difficulty in making a histologic diagnosis. This disease entity is also called osteochondroma; however, herein we have described its diagnosis as osteocartilaginous exostosis because the protruding mass, which consisted of newly developed bony trabeculae entirely lined with layers, which, though irregular, were similar to the normal epiphyseal growth, was considered to be an accessory ossicle, which usually beomesenlarged in the form of a growth anomaly or chondroid ossification.
Fig.
2. Lateral cranial tomogram on first visit.
The main presenting features are usually a painless, gradual difficulty in opening of the mouth, malocclusion, and a bony swelling of the zygomatic area.’ In this particular case,severeinability to open
Large exostosis of the mandibular coronoid process 561
Volume 69 Number 5
Fig.
Fig.
4.
5. Occipitomental
roentgenogram
on first visit.
Opening3 yearsafter surgery.
the mouth and a bony prominence of the zygomatic area, making the face asymmetric, were significant; there was no malocclusion. In view of the diagnosis, radiographic examinations such as occipitomental views are most usefu12; tomography2*3and panoramic radiography4-6 are recommended, as well. Recently, computed tomography has also been suggested as being useful.7 Bone scintigraphy has also been reported to be useful in detecting bone lesions delineated by the abnormal accumulation of 99mT~.8In this particular case, the tomography and CT scan we used were diagnostic. In regard to treatment, surgical removal has been reported in previous articles. The area is usually approached surgically either intraorally or extraorally. The intraoral approach has advantages in providing direct accessto an abnormal massof the coronoid processwithout either damaging the facial nerve or causing any cosmetic damage; however, its surgical exposure is not large enough to remove a large mass. So far, we have collected reports of 50 such cases; 41 can be evaluated with the exclusion of caseseither lacking adequate description or involving patients
Fig.
6. Specimen obtained during operation.
who refused surgery. More than half of these 41 cases were operated on intraorally; 7, extraorally (mainly by an incision over the zygomatic area); and
562
Asanami, Kasazaki, and Uchida
ORAL SURC ORAL MED ORAL PATHOL May 1990 3. Mohnac AM. Bilateral coronoid osteochondromas. J Oral Surg Anesth 1962;20:500-6. 4. Rowe NL. Bilateral developmental hyperplasia of the mandibular coronoid process. A report of two cases. Br J Oral Surg 1963;1:90-104. 5. Cooper JC, Finch LD. Coronoid osteochondroma presenting as a coronozygomatic ankylosis. A case report. Br Dent J 1974;137:99-101. 6. James RB, Alexander RW, Traver JG. Osteochondroma of the mandibular coronoid process. Report of a case. ORAL SURC ORAL MED ORAL PATHOL 1974;37:189-95. 7. Ishii J, Amagasa T, Akashi K., Shioda S, Yuki K. Restricted jaw movement due to osteochondroma of the mandibular coronoid process: report of two cases. Jpn J Oral Maxillofac Surg 1983;29:507-13. 8. Kawaguchi Y, Shioda S, Akimoto Y, Yokoya S, Shioiri S, Kenji H. A case report of trismus caused by the hyperplasia of the coronoid process. Jpn J Oral Maxillofac Surg 1987;33:82531. 9. Dingman RO, Navig P. Reduced mandibular motion due to osteochondroma of the coronoid process of the mandible. Am J Surg 1957;94:907-10. 10. Fitzpatrick BN. Bilateral hyperplasia of the mandibular coronoid process. ORAL SURG ORAL MED ORAL PATHOL 1970;29:184-90. 11. Nishijima K, Fujii Y, Baba N, Hayase I. Limited opening of the mouth caused by exostosis of the left coronoid process of the mandible: renort of a case. Jpn J Oral Maxillofac Sura 1972;18:473-9. . 12. Monks FT. Bilateral hyperplasia of the mandibular coronoid processes: a case report. Br J Oral Surg 1978;16:31-7. 13. Rivas PH. Reduction of mouth opening due to mandibular coronoid process enlargement. ORAL SURG ORAL MED ORAL PATHOL 1979;47:131-4.
Fig. 7. Histopathologic findings. (Hematoxylin eosin stain. Original magnification, X40.)
and
7, by both methods, as we did. In 6 of these 7 patients, an incision was made intraorally along the anterior border of the mandible and externally on the zygomatic area to remove the mass.7,9-13 REFERENCES 1. Shackelford RT, Brown WH. Restricted jaw motion due to osteochondroma of the coronoid process. J Bone Joint Surg 1949;31(A):107-14. 2. Holmes FH. Mandibular block by osteochondroma of the coronoid process. Radiology 1956;67:578-81.
Reprint requests to: Dr. Souichiro Asanami Department of Dentistry School of Medicine Keio University 35 Shinanomachi Shinjuku-ku Tokyo, Japan
and Oral Surgery
coronoid
Report of a case Souichiro Asanami, DDS, PhD,a and Yasunori Kasazaki, DDS,a and Ikuhiro Uchida, DDS,b Tokyo, Japan KEIO
UNIVERSITY
AND
TOKYO
METROPOLITAN
KOMAGOME
HOSPITAL
The clinical experience of a patient with a large exostosis who had a chief complaint of difficulty in opening the mouth is reported. Radiographic examinations, especially tomography and a CT scan, were useful in the diagnosis. Surgical removal is the treatment of choice. The lesion is usually approached by a combination of intraoral and buccal routes; we also employed such an approach in this particular case. (ORAL SURC ORAL MED ORAL PATHOL
1990;69:559-62)
P
atients with an oral disease often come to us with complaints of difficulty in opening the mouth; however, this trouble rarely results from disorders of the coronoid process. We herein report our experience with a patient who had a diagnosis of exostosis of the coronoid process whose chief complaint was severe difficulty in opening the mouth. CASE REPORT
A 17-year-old male patient came to our department with a chief complaint of difficulty in opening his mouth. Patient and family histories were noncontributory. The history of the present illness went back to the age of 13 years, when the patient had a slight opening difficulty, joint grating, and a prominence of the left cheek, but his condition was initially left untreated. After that, a diagnosis of temporomandibular arthrosis was reached and a bite splint was placed in his mouth at a hospital; however, no improvement was observed. In May 1982, therefore, he visited a university hospital and was told, on the basis of radiographic examinations, that he had an enlarged left mandibular coronoid process.After that, progression of his difficulty in opening the mouth and a gradual enlargement of the prominence of the left cheek brought him to our department in April 1984. Physical examination determined that he was well developedand well nourished. Chest radiographs and EKG were normal. Laboratory data were within normal limits aDepartment of Dentistry and Oral Surgery, School of Medicine, Keio University, Tokyo, Japan. bDepartment of Oral Surgery, Tokyo Metropolitan Komagome Hospital.
7/12/11391
except for an elevated creatine phosphokinase level. The face was asymmetric because of a bony mass protruding into the left cheek. The skin covering it remained normal in color, without any tenderness or fever. The maximum distance of opening of the mouth was 8 mm. The central line of the mandible was slightly deviated to the left (Fig. 1). At the time of jaw movement, the right mandibular head moved anteriorly without any audible crepitation or grating; however, the left one did not move. The bilateral submandibular lymph nodes were not palpable. Radiographic jindings. Tomography revealed a welldemarcated radiopaque bony shadow extending continuously both anterosuperiorly and laterally from the left mandibular coronoid process (Fig. 2). An occipitomental film and cranial CT scan showed that the radiopaque shadow originated in the coronoid process,extended with a thick pedicle, and ended with a mushroom-shaped apex, and that the zygomatic bone, compressed by the lesion, protruded laterally (Fig. 3). With a tentative diagnosis of an enlarged left mandibular coronoid process,surgery was undertaken, with the patient under general anesthesia, in August 1984. The lesion was approached from both the inside and outside of the oral cavity. Incision was made continuously from the gingivobuccal transition at the maxillary molar area to the anterior ramus of the mandibule. The mucoperiosteal flap was bluntly dissected. Then, the coronoid process was exposed. It was amputated at its base to enable him to open his mouth. A transverse incision was made on the skin over the zygomatic bone, which was then opened to remove the mass.The tissue swelling disappeared 7 days after surgery, and the mouth-opening distance improved to 25 mm. It became 37 mm 1 month after surgery and 48 mm 2 months after surgery (Fig. 4). By that time, he did not have any difficulty in jaw movement or facial nerve palsy. The mouth-opening distance became 64 mm 559
560
Asanami, Kasazaki, and Uchida
ORAL SURG ORAL MED ORAL PATHOL May 1990
Fig.
Fig.
1. Maximum opening at first visit.
3. Cranial CT scan on first visit.
without any jaw deviation within 3 years (in August 1987). A radiograph demonstrated that the left mandibular coronoid processwas defective and that the mandibular ramus below the area seemedto have a thicker cortical bone than the opposite side (Fig. 5). The mass removed was measured as 51 X 45 X 25 mm, and its tip, protruding like a bow from the coronoid process,consisted mostly of a bony core in addition to a rim of a chondroid structure (Fig. 6). Histopathologic findings revealed that the protruded mass was mainly composedof newly developed bony trabeculae, whereas its bone marrow was identified as a fatty marrow. As for the connective tissue surrounding the lesion, all the layers were observed to be similar, though irregularly, to the normal epiphyseal growth. In the outer layer of the cartilage cap, slightly immature fibrous mesenchymal cells were also observed. The histopathologic diagnosis of osteocartilaginous exostosis was, therefore, established (Fig. 7). DISCUSSION
Histologic classifications of bone tumors differ depending on the sites involved, and the nomenclature used is not always consistent. There is thus some difficulty in making a histologic diagnosis. This disease entity is also called osteochondroma; however, herein we have described its diagnosis as osteocartilaginous exostosis because the protruding mass, which consisted of newly developed bony trabeculae entirely lined with layers, which, though irregular, were similar to the normal epiphyseal growth, was considered to be an accessory ossicle, which usually beomesenlarged in the form of a growth anomaly or chondroid ossification.
Fig.
2. Lateral cranial tomogram on first visit.
The main presenting features are usually a painless, gradual difficulty in opening of the mouth, malocclusion, and a bony swelling of the zygomatic area.’ In this particular case,severeinability to open
Large exostosis of the mandibular coronoid process 561
Volume 69 Number 5
Fig.
Fig.
4.
5. Occipitomental
roentgenogram
on first visit.
Opening3 yearsafter surgery.
the mouth and a bony prominence of the zygomatic area, making the face asymmetric, were significant; there was no malocclusion. In view of the diagnosis, radiographic examinations such as occipitomental views are most usefu12; tomography2*3and panoramic radiography4-6 are recommended, as well. Recently, computed tomography has also been suggested as being useful.7 Bone scintigraphy has also been reported to be useful in detecting bone lesions delineated by the abnormal accumulation of 99mT~.8In this particular case, the tomography and CT scan we used were diagnostic. In regard to treatment, surgical removal has been reported in previous articles. The area is usually approached surgically either intraorally or extraorally. The intraoral approach has advantages in providing direct accessto an abnormal massof the coronoid processwithout either damaging the facial nerve or causing any cosmetic damage; however, its surgical exposure is not large enough to remove a large mass. So far, we have collected reports of 50 such cases; 41 can be evaluated with the exclusion of caseseither lacking adequate description or involving patients
Fig.
6. Specimen obtained during operation.
who refused surgery. More than half of these 41 cases were operated on intraorally; 7, extraorally (mainly by an incision over the zygomatic area); and
562
Asanami, Kasazaki, and Uchida
ORAL SURC ORAL MED ORAL PATHOL May 1990 3. Mohnac AM. Bilateral coronoid osteochondromas. J Oral Surg Anesth 1962;20:500-6. 4. Rowe NL. Bilateral developmental hyperplasia of the mandibular coronoid process. A report of two cases. Br J Oral Surg 1963;1:90-104. 5. Cooper JC, Finch LD. Coronoid osteochondroma presenting as a coronozygomatic ankylosis. A case report. Br Dent J 1974;137:99-101. 6. James RB, Alexander RW, Traver JG. Osteochondroma of the mandibular coronoid process. Report of a case. ORAL SURC ORAL MED ORAL PATHOL 1974;37:189-95. 7. Ishii J, Amagasa T, Akashi K., Shioda S, Yuki K. Restricted jaw movement due to osteochondroma of the mandibular coronoid process: report of two cases. Jpn J Oral Maxillofac Surg 1983;29:507-13. 8. Kawaguchi Y, Shioda S, Akimoto Y, Yokoya S, Shioiri S, Kenji H. A case report of trismus caused by the hyperplasia of the coronoid process. Jpn J Oral Maxillofac Surg 1987;33:82531. 9. Dingman RO, Navig P. Reduced mandibular motion due to osteochondroma of the coronoid process of the mandible. Am J Surg 1957;94:907-10. 10. Fitzpatrick BN. Bilateral hyperplasia of the mandibular coronoid process. ORAL SURG ORAL MED ORAL PATHOL 1970;29:184-90. 11. Nishijima K, Fujii Y, Baba N, Hayase I. Limited opening of the mouth caused by exostosis of the left coronoid process of the mandible: renort of a case. Jpn J Oral Maxillofac Sura 1972;18:473-9. . 12. Monks FT. Bilateral hyperplasia of the mandibular coronoid processes: a case report. Br J Oral Surg 1978;16:31-7. 13. Rivas PH. Reduction of mouth opening due to mandibular coronoid process enlargement. ORAL SURG ORAL MED ORAL PATHOL 1979;47:131-4.
Fig. 7. Histopathologic findings. (Hematoxylin eosin stain. Original magnification, X40.)
and
7, by both methods, as we did. In 6 of these 7 patients, an incision was made intraorally along the anterior border of the mandible and externally on the zygomatic area to remove the mass.7,9-13 REFERENCES 1. Shackelford RT, Brown WH. Restricted jaw motion due to osteochondroma of the coronoid process. J Bone Joint Surg 1949;31(A):107-14. 2. Holmes FH. Mandibular block by osteochondroma of the coronoid process. Radiology 1956;67:578-81.
Reprint requests to: Dr. Souichiro Asanami Department of Dentistry School of Medicine Keio University 35 Shinanomachi Shinjuku-ku Tokyo, Japan
and Oral Surgery