title: Epithelioid myoepithelioma of the hard palate.
abstract: BACKGROUND
  Myoepithelioma, a generally benign tumor comprised of myoepithelial cells, is an uncommon salivary gland tumor. Among four morphologic variants of myoepithelioma, epithelioid type has not been reported in the oral and maxillofacial region.
  
  
  METHODS
  A 61-year-old man first noticed the mass 3 years previously. The oral examination revealed a firm, non-tender, and well-circumscribed mass in the middle of the hard palate. A magnetic resonance imaging scan showed a well-circumscribed mass with low signal intensity (T(1)-weighted image) or increased signal intensity (T(2)-weighted image).
  
  
  CONCLUSIONS
  Immunohistochemically, the tumor cells in the present case reacted to the epithelial (CK HMW and CAM5.2) and the mesenchymal (vimentin) markers. However, myoepithelial markers (S-100 protein, α-smooth muscle actin, glial fibrillary acidic protein, and calponin), except p63, were not expressed in the tumor cells. These results indicated that the epithelial myoepithelioma cells differentiated into epithelial cells rather than myoepithelial cells. We believe that epithelioid myoepithelioma of the palate is a distinctive subtype of myoepithelioma that should be included in the differential diagnosis of tumors of the palate.
authors.affiliation: Division of Dentistry and Oral-Maxillofacial Surgery, Chiba University Hospital, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. kasamatsua@faculty.chiba-u.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kasamatsu
authors.forename: Masashi
authors.initials: M
authors.lastname: Shiiba
authors.forename: Dai
authors.initials: D
authors.lastname: Nakashima
authors.forename: Ken
authors.initials: K
authors.lastname: Shimada
authors.forename: Morihiro
authors.initials: M
authors.lastname: Higo
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishigami
authors.forename: Shunsaku
authors.initials: S
authors.lastname: Ishige
authors.forename: Katsunori
authors.initials: K
authors.lastname: Ogawara
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanzawa
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Uzawa
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009208:Myoepithelioma / Q000175:diagnosis* / Q000473:pathology; D010157:Palatal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D021362:Palate, Hard / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor