myoepithelial carcinoma is the malignant counterpart of myoepithelioma , tumor cells exclusively manifest myoepithelial differentiation . according to the world health organization ( who ) classification , myoepithelial carcinoma is referred to those lesions which are composed almost exclusively of tumor cells with myoepithelial differentiation . it is a rare neoplasm that has not been included in most reported surveys of salivary gland neoplasia . this category of tumor was added to the classification of salivary gland tumor as a distinct clinicopathological entity by the who in 1991 . in the armed forces institute of pathology database of salivary gland neoplasms , it constitutes < 1% of malignant epithelial neoplasms . in reported series , the majority of myoepithelial carcinomas occur in the parotid gland , with fewer tumors in the submandibular and minor salivary glands . among the reported cases , intraorally only 69 cases affecting minor salivary glands have been reported in the english literature . similar to benign myoepitheliomas , the palate is the most common intraoral site of involvement . the average age of patient at presentation is over 50 years and the tumor usually appears as an asymptomatic mass that slowly increases in size . other than salivary glands , this tumor also occurs in the breast , skin , nasal cavity , nasopharynx , larynx and lung . we herein report a rare case of myoepithelial carcinoma of a 55-year - old female at buccal mucosa , a rare location . to the best of our knowledge , there are only eight cases of myoepithelial carcinoma of buccal mucosa are reported in the literature . a 55-year - old female patient presented in the department of oral and maxillofacial surgery , punjab government dental college and hospital , amritsar complaining of swelling in the back region of right cheek . the history dates back to 4 months when patient felt a small , asymptomatic swelling in back region of right cheek which was spontaneous with no history of trauma or functional impairment , which gradually increased in size . patient got extracted her two right upper posterior teeth from some private practitioner and was on antibiotic and anti - inflammatory medication , but got no relief . therefore , patient was referred in our institution for diagnosis and management . on extraoral examination , there was no obvious facial asymmetry or swelling evident , no cervical lymph node was palpable . intraoral examination revealed an outgrowth involving buccal mucosa of right posterior region extending up to the right maxillary tuberosity region . outgrowth was approximately 3.0  1.5 cm in size , cylindrical in shape , sessile , pink in color , smooth in surface with few bosselated areas secondary to occlusal trauma [ figure 1a ] . on palpation , temperature of growth was not raised , firm in consistency , nontender , ill - defined margins with fixation to underlying structure . magnetic resonance imaging of face and neck was performed , showed well - defined mass measured 2.2  1.3  1.0 cm in size on right side of buccal mucosa lying anterior to the masseter muscle and lateral to the buccinator muscle [ figure 1b ] . ( b ) magnetic resonance imaging : coronal section , t2-weighted image shows a hyperintense lesion on right side of buccal mucosa lying anterior to the masseter muscle . ( c ) showing surgical site , covered with biodegradable collagen sheet after wide resection of tumor . ( d ) macroscopic view of tumor mass after excision patient was advised fine - needle aspiration cytology ( fnac ) of the lesion . basal cell adenoma , solid variant of adenoid cystic or mucoepidermoid tumor were also kept in differential diagnosis . based on the clinical presentation and fnac report diagnosis of pleomorphic adenoma of right buccal mucosa was made with a differential diagnosis of adenoma , solid variant of adenoid cystic and mucoepidermoid tumor . the wide excision of the lesion was performed under local anesthesia and wound was covered with a biodegradable collagen membrane dressing [ figure 1c ] . the specimen [ figure 1d ] was fixed in formalin and sent for histopathological examination . microscopic examination showed a malignant tumor mostly composed of cells arranged in nests and lobules , separated by thin fibrovascular septae in a background of fibromyxoid stroma . the tumor cells had clear to pale eosinophilic cytoplasm , pleomorphic nuclei with prominent nucleoli and brisk mitoses [ figure 2a  c ] . immunohistochemical reactions were carried out and positive reactions obtained for pan - cytokeratin [ figure 3a ] , vimentin [ figure 3b ] , p63 [ figure 3c ] and s-100 [ figure 3d ] . the ki-67 [ figure 3e ] index was high ( > 10% ) . on the basis of histopathological and immunohistochemical results focal infiltration to adjacent structures and comedo necrosis present ( h and e , stain ) immunohistochemistry . ( e ) ki-67 positive as the wide local resection of the lesion had already been performed , no further treatment was done except a chest radiograph , to rule out any distant metastasis , which was reported as normal . patient remained free of disease for 15 months and still on follow - up [ figure 4 ] . myoepithelial cells are ectodermally derived contractile cells , routinely identified in many normal tissues with a secretory function such as major and minor salivary glands , lacrimal glands , sweat glands , breasts , and the prostate . salivary gland neoplasms that frequently contain myoepithelial cells are pleomorphic adenoma , adenoid cystic carcinoma and epithelial - myoepithelial carcinoma of intercalated duct origin . neoplasms composed exclusively of myoepithelial cells are uncommon accounting for < 1% of all salivary gland tumors . most of these tumors are located in the parotid gland , while others occur in the sub - mandibular gland or in the accessory glands of the oral cavity ( hard and soft palate , lip , cheek , tongue , floor of the mouth , gingiva , retromolar area ) . they sometimes arise from the glands of the respiratory tract ( nasal cavity , nasopharynx , larynx , and lung ) . many of the reported tumors have been described as developing in pleomorphic adenomas or myoepitheliomas i.e. , myoepithelial carcinoma ex pleomorphic adenoma . patients are generally over 50 years of age , with both sexes being equally affected . sheldon was the first to identify myoepithelial salivary gland tumor as a distinct neoplastic entity , in 1943 , but myoepithelial carcinoma was first reported by stromeyer et al . , in 1975 . the 27 and 25 cases reported by yu et al . , and savera et al . hornick and fletcher have reported 101 myoepithelial tumors of soft - tissue that were not associated with salivary gland tissue . tortoledo et al . , have reported 37 carcinoma ex pleomorphic adenoma in their study , out of which only three cases were myoepithelial carcinoma . young et al . , have reported a myoepithelial carcinoma of the cheek in a patient with familial adenomatous polyposis . kane and bagwan presented a retrograde study of 51 cases of myoepithelial carcinoma of the salivary glands in a tertiary cancer center . out of 51 , 36 cases showed minor salivary glands involvement and only 15 cases affected major salivary glands . tenderness , pain , hoarseness , dysphagia , and weight loss are experienced by a few few patients . some patients with myoepithelial carcinoma ex pleomorphic adenoma have reported a sudden rapid increase in size of mass that had been present for many years . it may be 2 - 20 cm in largest dimension , nonencapsulated , nodular and soft to firm . however , in myoepithelial carcinomas that develop in pleomorphic adenomas ( carcinomas ex pleomorphic adenoma ) , the pleomorphic adenoma portion of the neoplasm manifests ductal differentiation . squamous differentiation is one of the manifestations of neoplastic myoepithelial cells and is acceptable as a minor component in myoepithelial carcinomas . the cellular configurations in myoepithelial carcinoma are the same as those in benign myoepithelioma these include spindle , plasmacytoid , epithelioid , clear and mixed cells . the epithelioid cell type is the most common and purely clear cell myoepithelial carcinomas are rare and hard to distinguish from other types of clear cell neoplasms . neoplastic myoepithelial cells are capable of producing prodigious amounts of basal lamina in some tumors , which appears as eosinophilic hyaline material . both nodular and diffuse patterns of growth occur , but the nodular pattern is more common . tumor cells are arranged as sheets , nests , or cords ; the latter has been referred to as the reticular pattern . perineural and vascular invasion are evident in many myoepithelial carcinomas . while marked cellular and nuclear pleomorphism , high number of mitotic figures and necrosis are indicative of malignancy . myoepithelial carcinoma is distinguished from myoepithelioma on the basis of infiltrative growth , cytologic abnormalities , or both . in our case , immunohistochemically myoepithelial cells in their normal environment , i.e. , in a gland not involved by neoplasm or inflammation , express ck14 , smooth muscle actin , muscle - specific actin , calponin , smooth muscle myosin , and p63 . non - neoplastic myoepithelial cells in an area adjacent to neoplasm or in an area of inflammation often also express s-100 protein and glial fibrillary acidic protein , neoplastic myoepithelial cells variably express immunoreactivity to these antigens . s-100 protein is often a sensitive marker for neoplastic myoepithelium , but is not specific for myoepithelial carcinoma since normal and neoplastic intercalated duct cells also sometimes express s-100 protein . p63 also appears to be a sensitive marker for myoepithelial differentiation , but normal and neoplastic ductal and epidermoid basal cells also express p63 . calponin was a more sensitive myoepithelial marker in the series reported by savera et al . it is also found that the proliferation index derived from immunostaining for ki-67 could differentiate between benign and malignant tumors , a proliferation index above 10% indicated malignancy . same proliferation index was used in our case , which was high ( > 10% ) , confirmed the malignant nature of tumor . complete excision with tumor - free margin remains the first choice of treatment , in spite of the possibilities of local recurrence and distant metastasis to lung , kidney and brain . the role of radiation in the treatment of malignant myoepithelioma is still controversial . in a study by stromeyer et al . , they found that the tumor is not sensitive to radiation , while takeda reported a good clinical response to radiation . chemotherapy was unsuccessful in controlling extensive diseases in four cases , but may have been helpful in another . different studies regarding recurrence and prognosis of myoepithelial carcinoma provided variable data . in a study of 25 patients published by savera et al . follow - up of 17 patients out of these 25 showed that 47% ( eight patients ) developed metastasis and 29% ( five patients ) died of disease after a mean of 32 months . 59% ( 10 patients ) were without any evidence of disease after a mean of 42.2 months . in another study , pontes et al . , reviewed 69 cases previously reported in english literature , concluded that 72.5% did not present recurrences or metastasis . however , recurrence was observed in 8.7% of cases and metastasis in 5.8% of cases , especially to the cervical lymph nodes and the lungs . a total of 4.3% of patients affected , died from the disease and in 8.7% the follow - up features were not specified . as it is a rare neoplasm , the clinical parameters and pathological factors for determining the prognosis of patients affected by myoepithelial carcinoma are not well - established , although cellular pleomorphism , p53 over - expression , extensive invasion to surrounding tissues , perineural permeation , and high cellular proliferation may be correlated with a poorer clinical outcome . complete excision with tumor - free margin remains the first choice of treatment , in spite of the possibilities of local recurrence and distant metastasis to lung , kidney and brain . the role of radiation in the treatment of malignant myoepithelioma is still controversial . in a study by stromeyer et al . , they found that the tumor is not sensitive to radiation , while takeda reported a good clinical response to radiation . chemotherapy was unsuccessful in controlling extensive diseases in four cases , but may have been helpful in another . different studies regarding recurrence and prognosis of myoepithelial carcinoma provided variable data . in a study of 25 patients published by savera et al . follow - up of 17 patients out of these 25 showed that 47% ( eight patients ) developed metastasis and 29% ( five patients ) died of disease after a mean of 32 months . 59% ( 10 patients ) were without any evidence of disease after a mean of 42.2 months . in another study , pontes et al . , reviewed 69 cases previously reported in english literature , concluded that 72.5% did not present recurrences or metastasis . however , recurrence was observed in 8.7% of cases and metastasis in 5.8% of cases , especially to the cervical lymph nodes and the lungs . a total of 4.3% of patients affected , died from the disease and in 8.7% the follow - up features were not specified . as it is a rare neoplasm , the clinical parameters and pathological factors for determining the prognosis of patients affected by myoepithelial carcinoma are not well - established , although cellular pleomorphism , p53 over - expression , extensive invasion to surrounding tissues , perineural permeation , and high cellular proliferation may be correlated with a poorer clinical outcome . sometime diagnosis of myoepithelial carcinoma is difficult only by histopathological examination so role of immunohistochemistry in diagnosis should be considered as elucidated in present case . the concept , histological feature , immunohistochemical features , genetic changes , treatment options , and prognosis of myoepithelial carcinoma should be further discussed to uncover more cases .
myoepithelial carcinoma is a rare neoplasm of salivary glands that account for < 1% of all salivary gland tumors . 
 the most common sites of involvement are major salivary glands mainly parotid gland . 
 intraorally , it can arise from minor salivary glands ; palate is the most common site of occurrence . 
 it also occurs in nasopharynx , paranasal sinuses , nasal cavity and larynx in head and neck region . 
 myoepithelial tumors were first described in 1943 . 
 their malignant variant , myoepithelial carcinoma , was first reported by stromeyer et al . , in 1975 , characterized by distinct morphologic heterogeneity and an infiltrative growth pattern into adjacent tissues . here 
 , we report a rare case of a 55-year - old female with myoepithelial carcinoma of buccal mucosa . 
 it was also rare because of unusual location of tumor . 
 our patient was treated with wide local resection and remained free of disease for 15 months .