|Year : 2015 | Volume
| Issue : 1 | Page : 11-14
Isolated masseter cysticercosis in a healthy woman
Ranjan Kumar Sahoo1, Santosh Kumar Subudhi2, Adyakinkar Panda1, Harshmohan Pathak2, Swagatika Panda3
1 Department of Radiology, Institute of Medical Science and SUM Hospital, Bhubaneswar, Odisha, India
2 Department of Oral and Facio Maxillary Surgery, Institute of Dental Science, Siksha 'O' Anusandhan University, Bhubaneswar, Odisha, India
3 Department of Oral Pathology, Institute of Dental Science, Siksha 'O' Anusandhan University, Bhubaneswar, Odisha, India
|Date of Web Publication||18-Feb-2015|
Dr. Ranjan Kumar Sahoo
Department of Radiology, Institute of Medical Science and SUM Hospital, Sector - 8, Kalinga Nagar, Ghatikia, Bhubaneswar - 751 003, Odisha
Source of Support: None, Conflict of Interest: None
We report a rare case of unilateral masseter muscle swelling in a 44-year-old female patient who was provisionally diagnosed as cysticercosis of master muscle on ultrasonography and magnetic resonance imaging. Intraoral excision of the cyst and histopathological examination confirm the mass as masseter cysticercosis.
Keywords: Cysticercosis, masseter, Taenia solium
|How to cite this article:|
Sahoo RK, Subudhi SK, Panda A, Pathak H, Panda S. Isolated masseter cysticercosis in a healthy woman. J Oral Maxillofac Radiol 2015;3:11-4
|How to cite this URL:|
Sahoo RK, Subudhi SK, Panda A, Pathak H, Panda S. Isolated masseter cysticercosis in a healthy woman. J Oral Maxillofac Radiol [serial online] 2015 [cited 2019 Nov 14];3:11-4. Available from: http://www.joomr.org/text.asp?2015/3/1/11/151642
| Introduction|| |
Cysticercosis of human being is a common helminthiatic infestation by the larval stage of tape pork worm (Taenia solium).  The tapeworm enters the human body occasionally due to ingestion of tapeworm eggs from contaminated water or uncooked food.  It is most commonly seen in human body within brain, spinal cord, subcutaneous tissue, striated muscle and orbit.  The clinical manifestation depends on the location and stage of development of the tapeworm. We report a case of left side masseter cysticercosis who presented with painful swelling of left side of face for 6 months of duration.
| Case Report|| |
A 44-year-old female patient reported to dental outpatient department with complaint of painful swelling over left side of face for 6 months duration. She had no history of trauma or insect bite over the cheek. She noticed gradual onset of left face swelling with increasing size and intermittent pain. She was vegetarian and never eaten pork. She had received multiple courses of antibiotics from local doctors with no significant benefit. On clinical examination, left side of face showed swelling of about 6 cm × 6 cm size extending anteriorly up to nasolabial fold, posteriorly up to tragus of left ear, inferiorly till lower boarder of mandible and superiorly up to zygomatic arch. The skin over the swelling was normal in color [[Figure 1]a]. On bimanual palpation, the swelling was firm, noncompressible, tender and fixed to masseter muscle on clenching of teeth. Intraoral examination revealed small bulging over left buccal mucosa with normal color. Left parotid gland opening was normal. Mandible movement was free and unrestricted. The mass size did not change with chewing or swallowing food.
|Figure 1: Ultrasonography image of left side face swelling (a) shows an anechoic cystic lesion with eccentric intracystic echogenic nodule (b) and surrounding hypoechoic collection inside left master muscle suggestive of masseteric cysticercosis with abscess formation. No vascularity is seen inside the cystic lesion in color Doppler study (c and d)|
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Complete hemogram and chest radiograph study were normal. Ultrasound examination of the swelling revealed a well-defined anechoic cyst of about 2.5 cm × 1.3 cm size with echogenic nodule inside and surrounding perilesional hypoechoic area. Color Doppler study of the mass showed no intralesional vascularity [[Figure 1]b-d]. Left masseteric cysticercosis with surrounding phlegmon was the ultrasound diagnosis. Magnetic resonance imaging of the face showed round to oval T1-weighted (T1-W) hypointense, T2-weighted (T2-W)/T2-W fat saturation hyperintense cystic lesion with diffusion restriction in diffusion weighted imaging and apparent diffusion coefficient inside left masseter muscle [Figure 2]. Radiological diagnosis was left masseter cysticercosis. She was operated through intraoral approach for cosmetic reason and the cystic mass was excised by piece meal [[Figure 3]a-c]. Histopathology examination confirmed the cyst as cysticercosis [[Figure 3]d]. She was given oral tablet albendazole 400 mg twice daily for 14 days. She was asymptomatic on follow up examination.
|Figure 2: Magnetic resonance image of face shows a cystic lesion inside left master muscle. The cystic lesion shows T1-weighted hypointense (a), T2-weighted (T2-W) hyperintense (b), T2-W fat saturation hyperintense signal (c and d) and diffusion restriction in diffusion weighted image (e) and apparent coefficient image (f)|
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|Figure 3: Intraoperative image shows intraoral excision of left masseteric cysticercosis lesion (a and b) and excised pieces of the lesion over table (c). Microphotograph (d) of the lesion shows a fibrous capsule with double layer inner membrane showing larval form of Taenia solium inside|
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| Discussion|| |
Taenia solium exists worldwide but is most prevalent in Mexico, Central and South America, Asia, India, sub-Saharan Africa, and China.  Human is the definite host in tape worm life cycle and is infected due to ingestion of tapeworm eggs from contaminated food, water, uncooked/under cooked pork meat or due to regurgitation of eggs into stomach from small intestine harboring gravid worm. The worm develops and excretes eggs in small intestine of human being. The egg reaches the pig (the intermediate host) intestine through fecal contamination and develops cysticercosis. The human becomes intermediate host occasionally due to regurgitation of eggs into stomach from small intestine by reverse peristalsis. The egg develops into encysted form of larvae (Cysticercosis cellulosae) and enters the blood stream and results cysticercosis in different organs of body.  Cysticerci can be found anywhere in the body but are most commonly detected in the brain, spinal cord, skeletal muscle, subcutaneous tissue, heart or eye. Isolated muscle and subcutaneous tissue involvement by cysticercosis is rare.  In our case only left masseter muscle was involved which is uncommon.
The clinical presentation of cysticercosis depends on the number and location of cysticerci as well as the extent of associated inflammatory responses or scarring. The living larva does not produce symptoms as it evades the immune system while a dead larva incites granulomatous inflammatory response and thus produces symptoms depending on the location.  Cysticercosis in muscle may present three type of manifestation such as myalgia, pseudotumor, and abscess or rarely the pseudohypertrophic type. In myalgia type, the patient complains of severe muscle pain due to acute inflammation caused by dead larva and leakage of cyst fluid. In pseudotumor or abscess type, the mass develops due to chronic inflammation with collection of fluid around the cyst following intermittent leakage of cyst fluid. The third and rare pseudohypertropic type develops due to calcification of scolex, thickening of capsule wall and retraction of cyst.  In our case, the patient presented with the second type of clinical manifestation.
Clinical diagnosis of cysticercosis is often difficult to make because of its diverse clinical manifestation. Biopsy of the lesion with histopthological examination showing larva or larva with scolex confirms the definitive diagnosis.
At present, wide range of serological assay are available for diagnosis and epidemiological study of cysticeroisis. Enzyme linked immune sorbent assay (ELISA) or enzyme linked immune electro transfer blot (EITB) of serum, saliva, cerebrospinal fluid are often used for immunodiagnosis of cystecercosis and associated with false positive and negative results. However T. solium cyst fluid antigen-based lymphocyte transformation test has more sensitivity and specificity than ELISA and EITB. Serological assay is negative in case of calcified stage of neurocysticercosis.  In our case we did not perform the serological assay for cystecercosis.
Fine-needle aspiration (FNA) diagnosis of cysticercosis is made when the aspirate contains larval fragments identified as lightly stained outer wavy membrane and multiple tiny ovoid nuclei in the fibrillary stroma.  No FNA was done in our case.
Ultrasonography (USG) examination with high frequency probe is the initial diagnostic modality of choice as it is inexpensive, readily available and nonionizing safe imaging modality. Ultrasound study of cysticercosis are usually four types depending on the development/rupture of cyst, healing of cystic lesion and surrounding inflammation Anechoic cyst with surrounding inflammatory mass may be seen due to death of larva. Irregular cyst with fluid collection in one side of cyst and non-visualization of intracystic echogenic nodule may be seen due to partial collapse or rupture of the cyst. Exudative particulate collection in muscle with anechoic cyst containing eccentric intracystic echogenic nodule is the common USG appearance as seen in our case. This appearance may be due to intermittent leakage of cyst fluid leading to chronic pericystic soft tissue inflammation. The fourth type of ultrasound appearance is like elliptical echogenic foci with posterior acoustic shadowing suggesting calcified cysticercosis which on radiograph shows typical millet seed like calcified nodules. 
Conventional radiography for cystecercosis are rarely done now a days. It detects the calcified cystecerosis as radio dense focus in the muscle.  Many patients are often advised for magnetic resonance imaging in case of soft tissue swelling. In MRI, the cyst shows T1-W hypointense, T2-W hyperintense signal with T2-W hypointense eccentric intracystic nodule as seen in our case. 
Computed tomography (CT) of brain for detection of neurocystecercosis is often helpful for diagnosis. However its role for detection of soft tissue cysticercosis is often not advised. The soft tissue cysticercosis appears as isodense to hypodense soft tissue mass in case of non-calcified cystecercosis and hyperdense mass in case of calcified lesion. Kumaru et al.  reported cystecercosis in temporalis muscle which was enhancing soft tissue mass like in CT scan imaging.
As FNA of the cyst may not provide the larval fragment always, the excisional biopsy of the lesion is the gold standard for diagnosis. Hematoxylline and eosin stained sections of soft tissue mass showed dense fibrous capsule infiltrated with inflammatory cells containing the cystecercus larva. The inner aspect of the capsule was a double-layered membrane in which larval form of T. solium were seen. Larva showed the presence of suckers and caudal to it duct-like invagination segment lined by homogenous membrane. Areas of dystrophic calcifications may be seen in the specimen. In our case there was no dystrophic calcification.
Treatment soft tissue cysticercosis depends on the location of cyst and associated complication. Surgical excision is advised for soft tissue cysticercosis with abscess. Cysts without abscess can be managed with antihelminthetics drugs (such as albendazole or praziquantel) alone. Follow up ultrasound examination is required after 3-4 weeks to see resolution of the lesion. 
| Conclusion|| |
In case of focal swelling of muscle or soft tissue, possibility of cysticercosis should be suspected. Ultrasound imaging of the swelling is initial imaging modality of choice. Soft tissue cysticercosis with abscess is managed by surgery while cysticercosis with no significant inflammation is managed conservatively.
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[Figure 1], [Figure 2], [Figure 3]