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Year : 2018  |  Volume : 14  |  Issue : 12  |  Page : 1237-1240

Ultrasonographic diagnosis of benign masseter muscle hypertrophy: A case report

1 Department of Oral Medicine and Radiology, Index Institute of Dental Sciences, Indore, Madhya Pradesh, India
2 Department of Periodontics, V.Y.W.S. Dental College and Hospital, Amravati, Maharashtra, India
3 Department of Conservative and Endodontics, Index Institute of Dental Sciences, Indore, Madhya Pradesh, India

Date of Web Publication11-Dec-2018

Correspondence Address:
Vihag Vinod Naphade
Department of Oral Medicine and Radiology, Index Institute of Dental Sciences, Indore, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0973-1482.204889

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 > Abstract 

Masseter hypertrophy is a characteristic condition resulting from an increase in the size of the muscle mass. At times, it produces significant facial asymmetry and is an important finding in the differential diagnosis of similar located entities. A proper diagnosis of this condition would avoid more aggressive and unwarranted therapy by an inexperienced clinician who may mistake it for a more serious pathologic condition. This article reports two cases of bilateral masseter hypertrophy having characteristic diagnostic features, along with specialized imaging modalities and review of literature.

Keywords: Case reports, hypertrophy, masseter muscle

How to cite this article:
Naphade VV, Kedia SG, Patil P, Khare S. Ultrasonographic diagnosis of benign masseter muscle hypertrophy: A case report. J Can Res Ther 2018;14, Suppl S5:1237-40

How to cite this URL:
Naphade VV, Kedia SG, Patil P, Khare S. Ultrasonographic diagnosis of benign masseter muscle hypertrophy: A case report. J Can Res Ther [serial online] 2018 [cited 2020 Jul 15];14:1237-40. Available from: http://www.cancerjournal.net/text.asp?2018/14/12/1237/204889

 > Introduction Top

In 1880, a case of bilateral hypertrophy of the masseter muscles and the temporalis muscle was described as in a 10-year-old girl.[1] Although few cases have been documented since then, it has been stated that this disorder is more common than generally recognized.[2] It is characterized by unilateral or bilateral enlargement of the masseter muscles and is often accompanied by pain, which may be intermittent and confused with parotid gland swelling.[3],[4] This paper reports the two cases of masseter muscle hypertrophy diagnosed using imaging modalities such as conventional radiography and ultrasonography (USG) along with a review of literature.

 > Case Reports Top

Case 1

An 18-year-old male patient reported to Department of Oral Medicine and Radiology with a chief complaint of a static swelling in lower one-third of the face since 1 year. The swelling is not associated with any pain and only cause an esthetic problem. On extraoral examination [Figure 1] there was a prominent swelling on clenching which was nontender and firm in consistency, also there was no intraoral counterpart associated with the swelling. Conventional radiography [Figure 2] showed bilateral homogeneous bony enlargement, more prominent at the left angle of the mandible. USG revealed increased thickness of masseter muscle on the left side [Figure 3].
Figure 1: Extra oral examination of the patient

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Figure 2: Conventional radiograph revealed bilateral homogenous bony enlargement

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Figure 3: Ultrasonography reveaked increased thickness of masseter muscle on left side

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Case 2

A 20-year-old female patient reported to the Department of Oral Medicine and Radiology chief complaint of a well-defined, unilateral swelling on the right side of angle of mandible which was noticed 5 months back and has not changed in size since then [Figure 4]. A complaint of intermittent pain during mastication was recorded. Extraoral examination revealed a firm well-defined round swelling at the angle of mandible which became prominent on clenching. Patient's mouth opening was not reduced and temporomandibular joint was normal.
Figure 4: Extra oral examination revealed unilateral swelling on right side

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There was no intraoral counterpart to the swelling, or any odontogenic source of infection and occlusal contacts were intact. Her orthopantograph revealed no significant findings; however, there was a uniform bony enlargement of the right angle of mandible in comparison to the left side on anteroposterior view of the skull radiograph [Figure 5]. Her USG revealed an increase in the masseter muscle thickness of the right side [Figure 6].
Figure 5: Skull radiograph revealed unilateral enlargement of right angle of mandible

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Figure 6: Ultrasonography revealed increase in masseter muscle thickness of right side

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None of the two cases gave a history of trauma, altered taste sensation, drying of mouth, difficulty in swallowing or mastication, ear infection or similar swelling anywhere else in the body. Interestingly, none of the two cases gave a history of gum chewing or unilateral mastication or teeth clenching. Furthermore, their medical history was not contributing. Considering the age, sex, clinical appearance radiographic, and other investigatory findings, final diagnosis of benign masseter muscle hypertrophy was made.

 > Discussion Top

Legg[1],[5] in 1880 was the first to report this condition in a 10-year-old girl, a case of bilateral hypertrophy of masseter muscles and temporalis. Although few cases have been documented since then, and it has been stated that this disorder is more common than generally recognized. It is characterized by unilateral or bilateral enlargement of the masseter muscles and is often accompanied by pain which may be intermittent and confused with parotid gland swelling.

Rispoli et al.[5] mentioned that according to the literature clenching, bruxism during sleep, malocclusion, temporomandibular joint disorder, unilateral chewing, and gum chewing are considered the most possible cause of masseteric hypertrophy. There are several theoretical considerations about the etiology, but it still remains unclear as the patient may or may not be aware of his habit. Thus, physical examination through intra- and extra-oral palpation of an inflammation free muscle serves to support the diagnosis.

Black and Schloss[6] while reporting three cases of masseteric muscle hypertrophy stated the importance of computed tomography (CT) scan in diagnosing this condition. Other investigatory modalities include magnetic resonance imaging (MRI) and USG. It is stated by Sannomya et al.[7] that USG was useful in diagnosing cases with facial asymmetry. A study conducted at the University of Goteborg, Sweden[8] in 1991 with forty patients also stressed on the efficacy of ultrasound imaging technique in revealing variation in the thickness of masseter muscles since the investigation was noninvasive and performed on a larger surface area available on ramus region. USG can thus be considered reliable and economical in comparison to advanced modalities such as CT scan and MRI. Our case reports were also diagnostically proven using the USG technique. Thus, the benign masseter muscle hypertrophy diagnosis is eminently clinical and is based on the identification of symptoms and cosmetic facial alterations. A misdiagnosis of this clinical entity will result in irreparable damage to the vital structures lying in the same region. Emphasis must be placed on the differential diagnosis of this condition which would include the following:[9]

  1. Salivary gland: Benign and malignant tumors arising from accessory parotid gland or duct
  2. Inflammation/infection: Abscess or cellulitis by specific or nonspecific infection
  3. Lymphatic system: Metastatic lymph node, lymphadenitis, lymphoma, lymphamgioma
  4. Connective tissue: Lipoma, fibroma, or pseudotumour
  5. Myopathy: Masseter hypertrophy, myositis ossificans, proliferative periostitis
  6. Vascular system: Hemangioma, A-V malformations, or false aneurysms.

Reviewing the present case reports clinical facts to be borne in mind which will otherwise differentiate the present clinical condition from other entities are:[10]

  1. A uniform mass of long duration
  2. A characteristic location in bucco-masseteric region
  3. Local muscle contraction produced by clenching of teeth which increase both the prominence as well as firmness which is characteristic when the muscle is contracted
  4. A more uniform swelling in contrast to the nodular and irregular swellings caused by a tumor.

Treatment for masseteric enlargement is usually unnecessary. Nonsurgical modalities of treatment include reassurance, tranquilizers or muscle relaxants, psychiatric care, and injection of very small doses of botulinum toxin type A. Dental restorations and occlusal adjustments to correct premature contacts and malocclusions are important. Parafunctional habits must be prevented.

Masseter muscle hypertrophy is a benign condition that usually does not require surgical intervention. Misdiagnosed cases due to lack of familiarity with this entity may lead to unnecessary biopsies, explorative surgeries, and even radiotherapy for suspected parotid tumors. The final diagnosis is thus eminently based on history of the patient, clinical findings, and findings of imaging modalities.

 > Conclusion Top

Benign masseter muscle hypertrophy is a disease of obscure etiology that may involve anyone. Although the diagnosis is strongly clinical, complementary exams may aid in the differential diagnosis against other conditions. The choice of treatment depends on the experience and skills of the surgeon.

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Conflicts of interest

There are no conflicts of interest.

 > References Top

Legg JW. Enlargement of the temporal and masseter muscles on both sides. Trans Pathol Soc Lond 1880;3:361-6.  Back to cited text no. 1
Fyfe EC, Kabala J, Guest PG. Magnetic resonance imaging in the diagnosis of asymmetrical bilateral masseteric hypertrophy. Dentomaxillofac Radiol 1999;28:52-4.  Back to cited text no. 2
Nishida M, Iizuka T. Intraoral removal of the enlarged mandibular angle associated with masseteric hypertrophy. J Oral Maxillofac Surg 1995;53:1476-9.  Back to cited text no. 3
Newton JP, Cowpe JG, McClure IJ, Delday MI, Maltin CA. Masseteric hypertrophy? preliminary report. Br J Oral Maxillofac Surg 1999;37:405-8.  Back to cited text no. 4
Rispoli DZ, Camargo PM, Pires JL Jr., Fonseca VR, Mandelli KK, Pereira MA. Benign masseter muscle hypertrophy. Braz J Otorhinolaryngol 2008;74:790-3.  Back to cited text no. 5
Black MJ, Schloss MD. Masseteric muscle hypertrophy. J Otolaryngol 1985;14:203-5.  Back to cited text no. 6
Sannomya EK, Gonçalves M, Cavalcanti MP. Masseter muscle hypertrophy: Case report. Braz Dent J 2006;17:347-50.  Back to cited text no. 7
Morse MH, Brown EF. Ultrasonic diagnosis of masseteric hypertrophy. Dentomaxillofac Radiol 1990;19:18-20.  Back to cited text no. 8
Sano K, Ninomiya H, Sekine J, Pe MB, Inokuchi T. Application of magnetic resonance imaging and ultrasonography to preoperative evaluation of masseteric hypertrophy. J Craniomaxillofac Surg 1991;19:223-6.  Back to cited text no. 9
Kiliaridis S, Kälebo P. Masseter muscle thickness measured by ultrasonography and its relation to facial morphology. J Dent Res 1991;70:1262-5.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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