Calcified Cystic Echinococcosis in Masseter Muscle-A Rare Case and Literature Review

Introduction: Echinococcus granulosus is a small intestinal tapeworm found in dogs and occasionally in other carnivores. In the literature, information on the incidence of Echinococcus manifestations in the head (noncerebral) and neck region is relatively rare. Purpose: To present a case of an unusual case of echinococcus in the masseter muscle of a young female patient at the Department of Oral and maxillofacial surgery, University Hospital St. . Anna, Sofia. Material and methods: The medical history of 14 years old female patient revealed a painless swelling of the left masseter muscle. Bimanual palpation showed two mobile thick lesions in the left masseter muscle. Pain and neurologic deficits were absent. Salivary flow was normal from the left Stennonis duct. The patient denied any prior medical problems. All hematologic parameters were within normal limits- no eosinophilia was evident. A computed tomography (CT) scan was obtained, and it showed two, well-defined lesion - parasite cysts in the left masseter muscle which were with high degree of calcification. The patient was scheduled to undergo excisional biopsy of the lesion under general anaesthesia. Result: Pathohystological examination showed the presence of the cyst parasite hooklets fully calcificated with characteristic for E. granulosus which were non active lesions (Hematoxylin and eosin stain original magnification _10. ) showed absence of scolexes). Conclusion: Although a rare event, echinococcosis must be considered in the differential diagnosis of head and neck tumours.