epithelial - myoepithelial carcinoma ( emc ) is a rare biphasic low grade malignancy accounting for only 0.5% of all salivary gland tumors .
there have been reports suggesting co - existence of another malignancy , like adenoid cystic carcinoma ( ad cc ) with emc , in the same tumor .
if emc develops in a long standing case of pleomorphic adenoma ( pa ) , it is called emc - ex pa .
ours is a case of a tumor in the submandibular and sublingual salivary glands diagnosed as emc , having clinical and histological resemblance to cellular pa .
the present case report is about a 61-year - old woman who reported to us with a growth in the floor of mouth that gradually increased in size since last 3 years , without pain . on examination , a 3 cm  2.5 cm
ovoid swelling was palpated lingual to the edentulous alveolar ridge , extending from midline ( lingual frenum ) to the right premolars [ figure 1 ] .
it was a firm , non - tender , non - compressible , non - reducible , did not move with deglutition and showed no change in size with meals .
complete hemogram , serum electrolyte levels , kidney function test and liver function test had all values within the normal range , but for a raised erythrocyte sedimentation rate ( 50 mm / h ) .
magnetic resonance imaging revealed a 20 mm  18 mm  15 mm well defined well - marginated lesion in right sublingual space in the region of anterior aspect of sublingual gland [ figure 2 ] .
it indented the inferior surface of tongue and right genioglossus muscle and did not cross midline .
multiple mildly enlarged bilateral level ib , ii and iii lymph nodes were noted . a provisional diagnosis of pa of sublingual gland was made and local excision of the lesion along with the gland was planned under l.a .
incision was placed from midline extending posteriorly near the alveolar ridge in order to protect the wharton 's duct . with careful dissection ,
, it was found that the mass involved the deep part of submandibular gland and duct with the sublingual gland being compressed by the mass .
it was difficult to delineate the exact origin of the pathology ( sublingual or submandibular gland ) ; hence it was decided to sacrifice the sublingual gland , deep part of submandibular gland and its duct on the affected side [ figure 1 ] .
initial histopathological examination , revealed a solid tumor tissue composed of myoepithelial and ductal cells presenting as double layered duct like structures with hyalinization of stroma .
the epithelial component showed diversity in the form of sheets , nests and cords with different patterns of ductal arrangements and large areas of secretory material in the intervening areas , suggestive of cellular pa [ figure 3 ] .
however since most of the tumors of submandibular and sublingual gland are malignant , a second examination of the specimen was undertaken .
it showed that the entire tumor mass was covered by dense band of fibrous connective tissue .
tumor cells were arranged in a background of predominantly mucous acini , as small tubules lined by cuboidal to oval cells containing prominent nuclei and eosinophilic cytoplasm and surrounded by clear cells and increased hyalinization [ figure 4 ] . on the basis of this dual cell population , a provisional diagnosis of emc was suggested .
some focal areas were also observed with cells arranged in a cribriform pattern with pseudocystic spaces that pointed toward ad cc .
immunohistochemistry showed p-63 reactivity in outer clear cells , s-100 and smooth muscle actin were focally positive and c - kit for ad cc was negative .
hence , a diagnosis of hybrid carcinoma was ruled out and a final diagnosis of epi - myoepithelial carcinoma was made .
there is a chance that being a long - standing tumor ; initial pa may have turned into emc .
patient denied adjuvant radiotherapy ; is being followed - up since last 1 year and has no fresh complains or signs of recurrence until now [ figure 5 ] .
magnetic resonance imaging of the lesion h and e section suggestive of cellular pleomorphic adenoma h and e section suggestive of epithelial - myoepithelial carcinoma post - operative clinical picture
emc was first described by donath et al . , in 1972 and officially defined as a salivary gland tumor by who in 1991 .
it commonly affects parotid gland ( 70% ) , sino - nasal glands , palatal and submandibular gland and rarer sites like lungs , breasts etc . , ( no reports on sublingual gland origin were found ) . it is a low - grade carcinoma of ductal origin characterized by its dual cell population of ductal epithelial cells and clear myoepithelial cells .
apart from this characteristic picture , there are many histological variants such as oncocytic emc , double clear emc , emc ex pa , high grade or dedifferentiated emc , emc with myoepithelial anaplasia etc .
many times , it is found that pre - operative fnac points toward a benign pathology ( pa ) .
a diagnosis of pa would be incorrect due to the excessive hyalinization seen in the tissue , in spite of the pleomorphic picture of cells .
differential diagnosis includes other clear cell tumors such as muco - epidermoid carcinoma , acinic cell carcinoma and sebaceous carcinoma , with immunohistochemical presence of myoepithelial markers , similar to those seen in emc .
furthermore , there have been reports describing emc ex pa in parotid gland with the histological picture similar to ours . within the characteristic dual cell picture of emc ,
arrangements of cells in cribriform pattern with pseudocystic spaces reminiscent of ad cc were observed focally .
, the tumor could have been a primary onset emc or an emc - ex - pa .
there have been cases of recurrence of tumor by simple excision alone , hence we chose wider margins of healthy mucosa .
the prognosis of emc is fairly good as the median disease free survival rate is reported to be 11.34 years .
long - term follow - up is needed for detection of early signs of recurrence and proper management .
 a 61-year - old female presented with a 3-year - old swelling in the right floor of mouth . clinical examination and fine needle aspiration cytology suggested a benign lesion . 
 the mass was excised locally along with the involved sublingual and deep part of submandibular gland and duct . 
 post - operative histopathological examination revealed features of pleomorphic adenoma . 
 however , on revision of histological sections , features were predominantly of a rare malignancy of the salivary glands , epithelial - myoepithelial carcinoma ( emc ) , along with focal areas of adenoid cystic carcinoma ( ad cc ) . 
 the tumor was p-63 , s-100 and smooth muscle actin positive but c - kit was negative , which ruled out ad cc and the possibility of a hybrid carcinoma . 
 the aim of this article is to describe a rare case of emc in the floor of mouth and the confusing cytological picture that it created . 