| Abstract|| |
Cysticercosis of the oral cavity is a very rare soft tissue lesion and very few cases have been reported worldwide. Here we report a case of a cysticercous cellulosae within the masseter muscle which was diagnosed with the help of high resolution ultrasonography (USG) and ultrasound guided fine needle aspiration cytology (FNAC) and managed conservatively using oral antiparasitic medication. Cysticercosis is not commonly considered in the diagnosis of swellings of the head and neck and this is the reason why they are of utmost interest to the practitioner and have to be studied.
Keywords: Cysticercus cellulosae, intramuscular cyst, masseter, sonography, taenia solium
|How to cite this article:|
Ramakrishnan P, Bahirwani S, Balaji P. Cysticercosis of the masseter. Indian J Dent Res 2012;23:436
Cysticercus cellulosae is a parasitic infection which is caused by the larval (cysticercus) stage of taenia solium (pork tapeworm). This disease is endemic to developing countries like Brazil, Chile, Ecuador, Mexico, South and East Africa, the Far East, and India  where there is poor access to sanitation facilities and close interaction between humans and animals. The presentation is extremely rare in the masseter muscle. Although it is very difficult to clinch the diagnosis of cysticercosis in the oral cavity, High resolution USG followed by FNAC has been of paramount importance as a diagnostic tool, even in cases where computed tomography (CT) and magnetic resonance imaging (MRI) fail to do so. 
| Case Report|| |
A 25-year-old female patient from the lower socioeconomic strata, a farmer by occupation, presented with a gradually increasing swelling in the left lower 1/3rd of the face since the past 3 months. However, she did not take any medication for the problem. She did not have any other abnormal medical history. She took a mixed diet and had no deleterious habits.Extraoral examination revealed no significant inspectory findings, however, on palpation a solitary roughly ovoid swelling was palpable within the left cheek region in the lower 1/3rd of the face. It measured approximately 1 × 1 cm and was situated mediolaterally 3.5 cm posterior to the left labial commissure and 2 cm anterior to the left angle of the mandible. It was firm, nontender, and freely mobile. However, the swelling became fixed when the patient was asked to clench her teeth, suggesting that the swelling probably had a masseter muscle involvement [Figure 1].
|Figure 1: Extra oral picture with an arrow pointing at the site of swelling.|
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On intraoral examination, there was a grossly decayed mandibular left third molar with deep dental caries in it. It was tender on probing, percussion, and palpation, with no associated lymphadenopathy [Figure 2]. A diagnosis of acute apical abscess was given for 38, and with respect to the swelling in the massetric region a diagnosis of submassetric abscess of left masseter was given and lipoma, fibroma, massetric hypertrophy, hemangioma, and mucocele were considered as differential diagnosis.
Radiographic examination revealed an ill-defined radiolucency in the apical 1/3rd of 38 and subsequently underwent extraction. The patient was given post-extraction instructions, analgesics and antibiotics and recalled after a week. Recall check up revealed a healed socket, however, there was no change in the swelling present in her left cheek region. Following which she was subjected to USG Examination, on a Logiq 500 PRO machine (GE Medical Systems) using a linear transducer probe at 11 MHz, a hypoechoic area suggestive of an intramuscular cystic lesion measuring approximately 10.2 × 6.8 × 9.2 mm was seen within the left masseter muscle. It showed well-defined margins, with a hyperechoic scolex attached to one end of the cyst wall, measuring approximately 4.6 × 1.8 mm. The cystic lesion was distinctly separated from the cortex of the ramus of the left hemi-mandible. Based upon the interpretation of the USG a diagnosis of an intramuscular cyst was suggested with probability of a parasitic etiology [Figure 3]
|Figure 3: High resolution sonogram of left cheek muscle showing a homogenous,hypoechoic lesion with a hyperechoic scolex.|
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A USG guided FNAC was performed [Figure 4], which yielded 2 ml of clear watery fluid with yellowish-white flakes. Smears were prepared from the aspirate using May-Grunwald Giemsa (MGG) staining. The cysticercus cellulosae, was identified and a histopathological diagnosis of cysticercosis was made based on the appearance of the thin cyst wall with a cellular laminated layer exhibiting the germinal membrane with scolices [Figure 5].
Blood, urine, and stool studies failed to show active parasitosis. The patient was given tablet albendazole 15 mg/kg body weight/day for 14 days. In addition, an oral dose of methyl prednisolone 2 mg/kg/day was given which was later tapered down over 14 days. A repeat ultrasound was performed after a month which showed no abnormality in the left masseter region save for a healed residua [Figure 6].
|Figure 6: Ultrasound picture demonstrating a healed residua in the region.|
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| Discussion|| |
Taenia solium is a hermaphrodite cestode that inhabits the human small intestine on ingestion of unwashed vegetables or inadequately cooked pork infected with viable larvae (cysticerci). The scolex of the larvae evaginates from the cyst inside the small intestine and attaches to the bowel wall. After around 12 weeks proglottids are formed which are generally excreted in feces causing taeniasis. The proglottid contains 50-60,000 eggs which can remain viable for a really long duration in water, soil and vegetation. The cysticercosis develops when these eggs are ingested by humans and the oncospheres (embryos) are released by the action of gastric acid and intestinal fluid and usually cross the intestinal wall and are carried via the blood stream and infect various tissues and organs where they develop into larval vesicles or cysticerci. ,
In the intramuscular cysticercosis, three distinct types of clinical manifestations have been described: the myalgic type; the mass-like, pseudotumor or abscess-like type, and the rare pseudohypertrophic type. , In all these types, the main diagnostic feature is the presence of the well-defined cystic lesion with an eccentric hyperechoic scolex in it, as was seen in this case. In addition to these, there is a fourth ultrasound appearance associated with calcified cysticercosis, which manifests as multiple elliptical calcifications in soft tissues, similar to pathognomonic millet seed-shaped elliptical calcifications seen on plain radiographs.  After USG interpretation, it is prudent to perform a FNAC to confirm the diagnosis before putting the patient on anti-helminthic therapy. Here, it was wise to do an USG guided FNAC procedure considering the difficulty in accurately localizing an area of such a small magnitude within the muscle. Definitive diagnosis can be made on FNAC which is now being increasingly accepted as a reliable diagnostic procedure. 
In conclusion, we suggest that cysticercosis should be considered in the differential diagnosis of solitary nodules within the oral and maxillofacial region. We also herald the role of high resolution USG and USG guided FNAC as the diagnostic tool in such cases and also suggests that localized parasitic infections like cysticercosis cellulosae can be treated successfully with conservative management using oral antiparasitic (antihelminthic) medication.
| Acknowledements|| |
Dr. Narayanan TV (M.D.S) and Dr. Padma Reddy (M.D) for being of immense aid in the histopathological analysis and Dr. Deepak Daryani (M.D.S) and Dr.Swapnil Bhagat (M.D) for their help and support
| References|| |
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Department of Oral Medicine and Radiology, Dr. Syamala Reddy Dental College, Hospital and Research Center, Bangalore
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]