Journal of Oral and Maxillofacial Radiology

: 2019  |  Volume : 7  |  Issue : 1  |  Page : 12--17

Isolated cysticercosis of masseter muscle in a young boy with trismus: Report of a case misdiagnosed as unilateral temporomandibular joint ankylosis

Jyoti Prajapat1, Rajesh Prajapat2, Puneeta Vohra1,  
1 Department of Oral Medicine and Radiology, SGT University, Gurugram, Haryana, India
2 Department of Prosthodontics, Crown and Bridge, Private Practitioner, Gurugram, Haryana, India

Correspondence Address:
Jyoti Prajapat
Plot No: 39, Ranaji Enclave, Near Arya Samaj Mandir, Opp. State Bank of India, Nangli Sakrawati, New Delhi - 110 043


Cysticercosis is a parasitic infection caused by the larval stages of Taenia solium. Cysticercosis is a potentially fatal parasitic disease that was rarely found in the maxillofacial region. This report suggests that cysticercosis should be considered in the differential diagnosis of chronic swelling in the oral and maxillofacial region and the importance of noninvasive modality ultrasonography (USG) in diagnosis. This paper reports a case of cysticercosis in the right masseter muscle in an 11-year-old boy who presented with recurrent swelling on the right side of the face with inability to open mouth, its clinical features, diagnostic modalities used, and management of the case. Cysticercosis should be considered in the differential diagnosis of chronic oral and maxillofacial swelling. High-resolution USG is an excellent noninvasive and cost-effective modality for the diagnosis and also suggests that this parasitic infection can be successfully treated with conservative management using antihelminthic medication.

How to cite this article:
Prajapat J, Prajapat R, Vohra P. Isolated cysticercosis of masseter muscle in a young boy with trismus: Report of a case misdiagnosed as unilateral temporomandibular joint ankylosis.J Oral Maxillofac Radiol 2019;7:12-17

How to cite this URL:
Prajapat J, Prajapat R, Vohra P. Isolated cysticercosis of masseter muscle in a young boy with trismus: Report of a case misdiagnosed as unilateral temporomandibular joint ankylosis. J Oral Maxillofac Radiol [serial online] 2019 [cited 2019 Jun 18 ];7:12-17
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Cysticercosis was first described by Johannes Udalric Rumler in 1555. Cysticercosis is caused by the larval stage of pork tapeworm, Cysticercus cellulosae. According to the literature reports, the prevalence of oral cysticercosis is 4.1%.[1] The most frequent sites of cysticercosis are subcutaneous tissue, brain, muscles, heart, liver, lungs, and peritoneum.[2] Maxillofacial cysticercosis is a rare infection with not >34 cases of oral involvement reported in the English literature. The most commonly involved intraoral sites include tongue (42.15%), lips (26.15%), and buccal mucosa (18.9%).[1] Various affected sites in oral and perioral tissues are muscles of mastication, muscle of the facial expression, suprahyoid muscles, and postcervical musculature and also as in the tongue, buccal mucosa, and lip.[1] It is extremely rare in the masseter muscle. Although it is very difficult to diagnose cysticercosis in the oral cavity, high-resolution ultrasonography (USG) and fine-needle aspiration cytology have been the important diagnostic tools.

 Case Report

An 11-year-old boy reported to our department with a chief complaint of swelling in his middle one-third of the right side of the face with reduced mouth opening for 6 months. The case was misdiagnosed as unilateral fibrous temporomandibular joint (TMJ) ankylosis and was under treatment for the same from the past 6 months. There was no history of trauma during childhood, discharge, and any increase or decrease in size of swelling during meals. The patient gives a history of mixed diet. Medical history was noncontributory. The patient's mother gives a history of weight loss, reduced appetite, and fever. The patient belongs to low socioeconomic status.

On general examination, he was conscious, cooperative having normal gait and was poorly built. Signs of pallor were appreciated in palpebral conjunctiva. The patient was afebrile at the time of examination.

On extraoral examination, facial asymmetry was noticed due to swelling in middle one-third of the right side of the face. On inspection, a solitary well-defined dome-shaped swelling of size approximately 5 cm × 6 cm seen in middle one-third of the right side of the face extending 2 cm behind the right labial commissure to 1 cm in front of the posterior border of the ramus of mandible. The skin overlying swelling was normal [Figure 1].{Figure 1}

On palpation, swelling was firm, nontender, noncompressible, and nonfluctuant. The right submandibular and preauricular nodes were firm, palpable, and slightly tender. There was restricted mouth opening with a maximum interincisal opening of 5 mm [Figure 2]. Although swelling was firm and freely mobile, it became fixed and bulged when the patient was asked to clench his teeth, suggesting that the swelling probably had a masseter muscle involvement.{Figure 2}

Intraoral examination was not possible due to reduced mouth opening. Mouth opening was 5 mm.

Hence, orthopantomogram (OPG) was advised to the patient, but it was also nonremarkable. Both temporomandibular joint spaces appear normal, no significant finding suggestive of ankylosis. Teeth were in mixed dentition phase with no pathology noted [Figure 3].{Figure 3}

Hence, on the basis of the above findings, the differential diagnoses of juvenile fibroma, intramuscular hemangioma, cysticercosis and intramuscular lipoma, and salivary gland neoplasm were considered. As OPG was unremarkable, the patient was referred for USG. USG was performed with a Voluson 730 scanner (GE Healthcare) using 12 Mhz linear transducer. USG showed a solitary well-defined mixed lesion showing a hypoechoic area suggestive of an intramuscular cystic lesion measuring approximately 0.88 cm × 0.49 cm × 1.92 cm with a hyperechoic scolex attached to one end of the cyst wall, measuring approximately 0.48 cm × 0.86 cm within the right masseter muscle. Surrounding muscle fibers were inflamed and enlarged [Figure 4]. Preauricular and submandibular lymph nodes were enlarged [Figure 5].{Figure 4}{Figure 5}

Based on the interpretation of the USG, a diagnosis of intramuscular cysticercosis of the right masseter was given. The patient was managed conservatively with tablet albendazole 15 mg/kg body weight/day for 14 days. A follow-up ultrasound was done after 15 days which revealed a reduction in size of the lesion. There was a complete resolution of swelling with improvement in mouth opening [Figure 6] and [Figure 7]. The patient's follow up was done for 3 months.{Figure 6}{Figure 7}


Tapeworm infection is more common in developing countries because of rural population, crowding, and poor sanitation which is the reason of greater contact between humans and pigs and thus more fecal contamination of food and water.[3]

Cysticercosis is basically the parasitic infection by the larval stage of Taenia solium. It occurs when a man is infested by the larva of T. solium, and humans act as a definitive host. It occurs due to the ingestion contaminated food and water or eating undercooked meat (pork) containing eggs of tapeworm. The most common sites for the lodgment of larva are subcutaneous tissue, brain, and muscles. Other locations are heart, liver, lung, and peritoneum. Most of the cysts remain viable for 5–10 years and then start degenerating, followed by vigorous host response. The natural history of cyst is to resolve by complete resorption or calcification.[4]

Maxillofacial cysticercosis is a rare infection with not >34 cases of oral involvement reported in the English literature.[1] There was no sex or age predilection in its occurrence.

Life cycle of cysticercosis

The life cycle of T. solium includes two natural hosts: swine as the intermediate host and humans as the definite host. When pork infected with cysticerci is consumed by the humans, the larva first enters the small intestine where it develops into an adult worm. The adult worm attaches itself to the intestinal mucosa by scolex equipped with four lateral suckers and a rostellum, which bears 25–50 hooklets [Figure 8].{Figure 8}

Through hooklets, the oncospheres cross the intestinal wall and local venules, enter systemic circulation, and are carried to different organs of the host (skeletal muscles, central nervous system, subcutaneous tissue, eye, etc.)[5]

Cysticercosis cellulosae, the encysted larval form of T. solium, can remain viable in various sites for as long as 10 years in humans. Living larvae escape immune recognition and do not elicit inflammation. However, when the larva dies, a vigorous granulomatous inflammatory response is induced comprising predominantly of plasma cells, lymphocytes, eosinophils, and macrophages. Later, in long-standing cases, the dead cyst is surrounded by a dense layer of fibrosis or calcification.[6]

The oral and maxillofacial region is rich in muscular tissue, despite that it is not a frequent site of occurrence for cysticercosis. In muscular involvement, three distinct types of clinical manifestations have been described: the myalgic type; the mass-like, pseudo-tumor, or abscess-like type; and the rare pseudohypertrophic type. Leakage of fluid from the cyst during death of larva induces acute inflammation resulting in local pain and myalgia. Degeneration of the cyst may result in leakage of fluid, which elicits a chronic inflammatory response, with collection of fluid around the cyst resulting in the mass-like type, the pseudo-tumor type, or the abscess-like type. Cysticercal larva often gradually reduces in size with capsular thickening and end-stage calcification.[7]

Solitary involvement of the masseter muscle presents as a bimanually palpable nontender, nodular, firm, mobile, gradually increasing swelling. Facial symmetry is undisturbed unless swelling becomes large. It may present as an acute inflammation with tender swelling. It is usually diagnosed as an inflammatory lesion of salivary gland or salivary neoplasm, with differentials including primary and metastatic tumors of the masseter muscle, sarcoidosis, lipomas, solitary neurogenic tumors, and vascular lesions.[6]

Cysticercosis is rarely included in the differential diagnosis preoperatively due to rarity of the condition and insufficient knowledge of various parasitic infections and their oral manifestations. Various radiological modalities such as USG, computed tomography (CT), and magnetic resonance imaging (MRI) are very effective in detecting cysticerci preoperatively. Our case is also diagnosed preoperatively by USG before performing histopathological examination. Histopathologic examination is the gold standard for the diagnosis of cysticercosis. Histopathologic examination helps in the diagnosis of cysticercosis by the detection of a cystic space containing C. cellulosae. Diagnosis can be done precisely with various serological laboratory methods.[8] Laboratory findings in patients with cysticercosis reveal eosinophilia, raised immunoglobulin E, and most importantly, a positive enzyme-linked immunosorbent assay test against C. cellulosae.[8]

Four different patterns of muscular cysticercosis on USG.[5]

The first pattern: Cystic cavity surrounded by inflammatory response which is due to the death of the larvaThe second ultrasonographic pattern: Irregularly defined cystic cavity with minimum fluid on one side, which indicates the leakage of fluid. Echogenic mass within the cyst is not seenThe third appearance: Muscle containing large irregular cyst having an eccentric placed echogenic foci. This appearance is similar to an intramuscular abscessThe fourth sonographic appearance: Calcified cysticercosis.

MRI is also helpful in the diagnosis of soft-tissue cysticercosis. Cysticercosis appears on MRI as a cystic lesion that appears hyperintense on T2-weighted and hypointense on T1-weighted images. MRI is also considered as the best tool for the investigation of degenerating and viable cysticerci in the nervous system, while CT is best for calcified lesions.[5]

There are reports of the ultrasonographic features of masseteric involvement of cysticercosis.[2],[9],[10],[11],[12]

Our patient showed the classical pattern, containing an eccentric echogenic focus within a cyst. Reddi et al. and Mittal et al. reported similar cases of intramuscular cysticercosis in the masseter muscle, both of which were diagnosed by USG and treated conservatively.[1]

Conventional radiographs are useful for the detection of muscle calcification.[13] Commonly radiodense images of the calcified cysticerci may appear on any radiograph of the soft tissues of the body. In the maxillofacial region, the most common locations of calcified cysticerci are muscles of mastication and facial expression, the suprahyoid muscle, and the posterior cervical as well as the tongue, buccal mucosa, or lip.[14]


There are five different modalities recommended for the treatment of cysticercosis [Figure 9].{Figure 9}

The management of cysticercosis is also site dependent. Antihelminthics such as albendazole (given in a dose of 15 mg/kg/day for 28 days) or praziquantel (administered in a dose of 50 mg/kg/day in three doses for 15 days) are effective for cysticercosis. Praziquantel, however, has no effect on calcified parasites. Low-dose steroid is also given with cysticidal drugs to prevent inflammatory reaction following death of larva.[5]


Cysticercosis should always be included in the differential diagnosis of maxillofacial swellings. High-resolution, noninvasive ultrasound plays an important role in diagnosing soft-tissue cysticercosis. However, histopathology is still the gold standard for confirmatory diagnosis. We also suggest that localized parasitic infections such as C. cellulosae can be successfully treated by conservative management using antihelminthic medication.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.


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