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Benign hypertrophy of the masseters
BENIGN HYPERTROPHY
OF T H E M A S S E T E R S
A Report of the Radiological Features in Two Cases P. M. DEE, M.B., B.S.
From the Department of Radiology, The Royal Victoria Infirmary, Newcastle upon Tyne IN 1880 Legg reported a case of bilateral hypertrophy of the masseter and temporal muscles in a ten-year-old girl. Since the first description only approximately forty cases of benign masseter hypertrophy have been reported in the literature, although Barton (1957) believes the condition to be relatively common. The hypertrophy of the masseters may be bilateral or unilateral: both types--but particularly the unilateral type--are commonly mistaken for parotid gland enlargement. The present cases were diagnosed as having parotid gland enlargement and were referred for sialography for this reason. The radiological features of benign masseteric hypertrophy are sufficiently distinctive to make a radiological diagnosis possible. These features do not appear to have been reported in the radiological literature, but Oppenheim and Wing (1959) give a good description of the radiological findings in their paper. The masseter is a quadrilateral muscle arising from the zygomatic process of the maxilla and the lower border of the zygomatic arch. The fibres pass down to be inserted into the angle and the lateral surface of the ramus of the mandible. The postero-inferior part of the muscle is related to the
antero-medial surface of the parotid gland. The superficial surface of the muscle is related to the accessory part of the gland and the parotid duct. The aetiology of hypertrophy of the masseters is not precisely known, but bilateral hypertrophy in some cases may be congenital or familial. Teeth grinding or clenching as a nervous habit or in sleep has been noted in several 'reported cases (Hersh 1946; Barton 1957). In other cases temporomandibular joint derangements or malocclusion cause the patient to chew mainly on the hypertrophied side. In the majority of cases no associated abnormality has been found. Clinically these patients are usually asymptomatic, although some complain of discomfort over the posterior part of the jaw and the temporomandibular joint. Usually patients seek advice because they or persons in contact with them have noticed lateral facial swellings. The swelling is over the ramus of the mandible and becomes firm on clenching the teeth, when the coarse bundles of the hypertrophied muscle can be palpated. In parotid gland enlargement the swelling is found more posteriorly under the lobe of the ear.
FIG. l FIG. 2 FIG. 1--The characteristic facies of the patient with bilateral masseteric hypertrophy is demonstrated by this photograph. FIG. 2 - Left par0tid sialogram demonstrating marked lateral displacement of the duct and flaring of the angles of the mandible. 347
348
CLINICAL RADIOLOGY
CASE REPORTS Case 1 . - - A fourteen-year-old girl (Fig. 1) was referred because of bilateral facial swellings associated with intermittent aching pain over the posterior part of the mandible of nine months duration. She gave a past history of mumps at the age of nine years. The facial swellings were thought to be enlarged parotid glands and sarcoidosis was considered as a possible cause. The patient had extensive in-patient investigations which included sialography.
The sialograms were reported initially as showing no abnormality. After the diagnosis of masseteric hypertrophy had been established a review of the films (Fig. 2) demonstrated :-1. Normal filling of the parotid glands with a duct of normal calibre. 2. Marked lateral displacement of the parotid duct and the accessory part of the gland from the normal position (Fig. 3). 3. Marked flaring of the angles of the mandible. It was realised that the lateral displacement of the ducts was produced by the bulk of the hypertrophied masseter muscles and that the flaring of the angles of the mandible was presumably secondary to the increased pull of the masseter muscles at their insertion. Examination of a series of photographs of this patient from early childhood suggested that the masseter hypertrophy had been present from an early age and that it might be considered one of the congenital type. Case 2 . - - A fifteen-year-old girl (Fig. 4) was referred to hospital because her mother had noticed a facial asymmetry which may have been present for several months. The patient was well and completely asymptomatic. She was referred for sialography with a diagnosis of left parotid gland enlargement.
FIG. 3 A normal parotid sialogram for comparison with the sialograms of the present cases.
This examination (Fig. 5) demonstrated a normal parotid gland and d u c t but marked lateral displacement of the parotid duct (for comparison with a normally situated parotid duct, see Figure 3). The duct was noted to course markedly in a lateral
FIG. 4 FIG. 5 FIG. 4--A photograph of the patient with unilateral masseteric hypertrophy. FiG. 5--Left parotid sialogram demonstrating lateral displacement of the duct but no flaring of angle of the mandible.
B E N I G N H Y P E R T R O P H Y OF THE MASSETERS
direction after leaving the gland before t u r n i n g in to open into the m o u t h . The duct was separated from the m a n d i b l e by a b o u t twice the n o r m a l distance a n d this was presumed to be due to masseteric hypertrophy. N o flaring of the angle of the m a n d i b l e was noted. After the radiological e x a m i n a t i o n the case was reviewed by the clinician and the diagnosis of masseteric hypertrophy was confirmed.
349
1. N o r m a l filling of the parotid gland. 2. Lateral displacement of the p a r o t i d duct a n d the accessory part of the parotid gland in the presence of a radiologically n o r m a l parotid gland. 3. Lateral flaring of the angles of the m a n d i b l e t h o u g h t to be due to the action of the hypertrophied muscles. Aeknowledgement.--I would like to thank Dr C. K. Warrick for his encouragement and constructive criticism.
SUMMARY Two cases of b e n i g n hypertrophy of the masseter muscles are reported, one of which was diagnosed radiologically. The radiological features are distinctive a n d consist o f : - -
BOOK
Edited by THOMAS LODGE, M.~., F.F.R., F.C.R.A.(HON.), D.M.R. Pp. 347, illustrated. London: Churchill. Price, 65s.
Recent Advances in Radiology--4th edition.
THIS is the 4th edition of a book originally published before the last war by Dr Peter Kerley. The vastly increased scope of radiology in recent years is reflected in the fact that the present editor, Dr Lodge, has given up the attempt to cover the whole field of radiology under single authorship. In the new edition there are twelve chapters and twelve authors. This is undoubtedly the only possible approach in these days of radiological specialisation. The problem of radiation dosage is reviewed by Ardran and Crooks in a chapter which collates much valuable information. The cardiovascular system is discussed by Steiner who contributes competent chapters on the heart, and on the pulmonary circulation. The complications of
REFERENCES BARTON, R. T. (1957). J. Amer. med. Ass. 164, 1646. HERSH, J. H. (1946). Arch. Otolaryng. 43, 593. LEGG, J. W. (1880). Trans. path. Soe. Lond. 31, 361. OPPE~-rEIM.H. & WING. M. (1959). Arch. Otolaryng. 70, 207.
REVIEW
gastric resection are discussed by Pulvertaft and the radiology of the small bowel and of the liver, spleen, gallbladder, and pancreas, are reviewed by Laws. Hodson discusses the kidneys and David Edwards contributes an excellent chapter on cysto-urethrography. Grainger also gives a first-class review of metabolic bone disease whilst Campbell contributes a small chapter on fractures of the facial bones. Chest disease is reviewed in a comprehensive chapter by Lodge and Darke. Finally, Lewtas discusses radiology of the central nervous system. It will be seen that this small volume covers a very wide field. All the chapters are well written, well edited and well illustrated. The book will be of considerable value not only to post-graduate students working for the D.M.R. and F.F.R., but to all practising radiologists. It is warmly recommended and should find a place in every departmental library. D.S.
OF T H E M A S S E T E R S
A Report of the Radiological Features in Two Cases P. M. DEE, M.B., B.S.
From the Department of Radiology, The Royal Victoria Infirmary, Newcastle upon Tyne IN 1880 Legg reported a case of bilateral hypertrophy of the masseter and temporal muscles in a ten-year-old girl. Since the first description only approximately forty cases of benign masseter hypertrophy have been reported in the literature, although Barton (1957) believes the condition to be relatively common. The hypertrophy of the masseters may be bilateral or unilateral: both types--but particularly the unilateral type--are commonly mistaken for parotid gland enlargement. The present cases were diagnosed as having parotid gland enlargement and were referred for sialography for this reason. The radiological features of benign masseteric hypertrophy are sufficiently distinctive to make a radiological diagnosis possible. These features do not appear to have been reported in the radiological literature, but Oppenheim and Wing (1959) give a good description of the radiological findings in their paper. The masseter is a quadrilateral muscle arising from the zygomatic process of the maxilla and the lower border of the zygomatic arch. The fibres pass down to be inserted into the angle and the lateral surface of the ramus of the mandible. The postero-inferior part of the muscle is related to the
antero-medial surface of the parotid gland. The superficial surface of the muscle is related to the accessory part of the gland and the parotid duct. The aetiology of hypertrophy of the masseters is not precisely known, but bilateral hypertrophy in some cases may be congenital or familial. Teeth grinding or clenching as a nervous habit or in sleep has been noted in several 'reported cases (Hersh 1946; Barton 1957). In other cases temporomandibular joint derangements or malocclusion cause the patient to chew mainly on the hypertrophied side. In the majority of cases no associated abnormality has been found. Clinically these patients are usually asymptomatic, although some complain of discomfort over the posterior part of the jaw and the temporomandibular joint. Usually patients seek advice because they or persons in contact with them have noticed lateral facial swellings. The swelling is over the ramus of the mandible and becomes firm on clenching the teeth, when the coarse bundles of the hypertrophied muscle can be palpated. In parotid gland enlargement the swelling is found more posteriorly under the lobe of the ear.
FIG. l FIG. 2 FIG. 1--The characteristic facies of the patient with bilateral masseteric hypertrophy is demonstrated by this photograph. FIG. 2 - Left par0tid sialogram demonstrating marked lateral displacement of the duct and flaring of the angles of the mandible. 347
348
CLINICAL RADIOLOGY
CASE REPORTS Case 1 . - - A fourteen-year-old girl (Fig. 1) was referred because of bilateral facial swellings associated with intermittent aching pain over the posterior part of the mandible of nine months duration. She gave a past history of mumps at the age of nine years. The facial swellings were thought to be enlarged parotid glands and sarcoidosis was considered as a possible cause. The patient had extensive in-patient investigations which included sialography.
The sialograms were reported initially as showing no abnormality. After the diagnosis of masseteric hypertrophy had been established a review of the films (Fig. 2) demonstrated :-1. Normal filling of the parotid glands with a duct of normal calibre. 2. Marked lateral displacement of the parotid duct and the accessory part of the gland from the normal position (Fig. 3). 3. Marked flaring of the angles of the mandible. It was realised that the lateral displacement of the ducts was produced by the bulk of the hypertrophied masseter muscles and that the flaring of the angles of the mandible was presumably secondary to the increased pull of the masseter muscles at their insertion. Examination of a series of photographs of this patient from early childhood suggested that the masseter hypertrophy had been present from an early age and that it might be considered one of the congenital type. Case 2 . - - A fifteen-year-old girl (Fig. 4) was referred to hospital because her mother had noticed a facial asymmetry which may have been present for several months. The patient was well and completely asymptomatic. She was referred for sialography with a diagnosis of left parotid gland enlargement.
FIG. 3 A normal parotid sialogram for comparison with the sialograms of the present cases.
This examination (Fig. 5) demonstrated a normal parotid gland and d u c t but marked lateral displacement of the parotid duct (for comparison with a normally situated parotid duct, see Figure 3). The duct was noted to course markedly in a lateral
FIG. 4 FIG. 5 FIG. 4--A photograph of the patient with unilateral masseteric hypertrophy. FiG. 5--Left parotid sialogram demonstrating lateral displacement of the duct but no flaring of angle of the mandible.
B E N I G N H Y P E R T R O P H Y OF THE MASSETERS
direction after leaving the gland before t u r n i n g in to open into the m o u t h . The duct was separated from the m a n d i b l e by a b o u t twice the n o r m a l distance a n d this was presumed to be due to masseteric hypertrophy. N o flaring of the angle of the m a n d i b l e was noted. After the radiological e x a m i n a t i o n the case was reviewed by the clinician and the diagnosis of masseteric hypertrophy was confirmed.
349
1. N o r m a l filling of the parotid gland. 2. Lateral displacement of the p a r o t i d duct a n d the accessory part of the parotid gland in the presence of a radiologically n o r m a l parotid gland. 3. Lateral flaring of the angles of the m a n d i b l e t h o u g h t to be due to the action of the hypertrophied muscles. Aeknowledgement.--I would like to thank Dr C. K. Warrick for his encouragement and constructive criticism.
SUMMARY Two cases of b e n i g n hypertrophy of the masseter muscles are reported, one of which was diagnosed radiologically. The radiological features are distinctive a n d consist o f : - -
BOOK
Edited by THOMAS LODGE, M.~., F.F.R., F.C.R.A.(HON.), D.M.R. Pp. 347, illustrated. London: Churchill. Price, 65s.
Recent Advances in Radiology--4th edition.
THIS is the 4th edition of a book originally published before the last war by Dr Peter Kerley. The vastly increased scope of radiology in recent years is reflected in the fact that the present editor, Dr Lodge, has given up the attempt to cover the whole field of radiology under single authorship. In the new edition there are twelve chapters and twelve authors. This is undoubtedly the only possible approach in these days of radiological specialisation. The problem of radiation dosage is reviewed by Ardran and Crooks in a chapter which collates much valuable information. The cardiovascular system is discussed by Steiner who contributes competent chapters on the heart, and on the pulmonary circulation. The complications of
REFERENCES BARTON, R. T. (1957). J. Amer. med. Ass. 164, 1646. HERSH, J. H. (1946). Arch. Otolaryng. 43, 593. LEGG, J. W. (1880). Trans. path. Soe. Lond. 31, 361. OPPE~-rEIM.H. & WING. M. (1959). Arch. Otolaryng. 70, 207.
REVIEW
gastric resection are discussed by Pulvertaft and the radiology of the small bowel and of the liver, spleen, gallbladder, and pancreas, are reviewed by Laws. Hodson discusses the kidneys and David Edwards contributes an excellent chapter on cysto-urethrography. Grainger also gives a first-class review of metabolic bone disease whilst Campbell contributes a small chapter on fractures of the facial bones. Chest disease is reviewed in a comprehensive chapter by Lodge and Darke. Finally, Lewtas discusses radiology of the central nervous system. It will be seen that this small volume covers a very wide field. All the chapters are well written, well edited and well illustrated. The book will be of considerable value not only to post-graduate students working for the D.M.R. and F.F.R., but to all practising radiologists. It is warmly recommended and should find a place in every departmental library. D.S.