title: High-grade epithelial-myoepithelial carcinoma of the parotid gland with mucous cell differentiation.
abstract: Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor with a low-grade malignancy, and EMC with high-grade histopathological features is exceedingly rare. Furthermore, EMC with intracellular mucin is also extremely rare. We report an uncommon case of a high-grade EMC of the parotid gland with mucous cell differentiation in a 66-year old Japanese woman who noticed a right palpable parotid mass increasing in size within a one-year period. The cytological specimen showed a focally biphasic structure and included isolated or discohesive piled-up clusters with hyaline globules surrounded by neoplastic cells with nuclear atypia. The gross examination revealed a relatively well-demarcated, multinodular gray-whitish and solid mass. Histologically, the tumor consisted of variably sized solid nests or trabeculae with central necrosis and increased mitotic activity, and invaded into adjacent skeletal muscles. Immunohistochemically, the biphasic ductal and myoepithelial differentiation of this tumor confirmed the diagnosis of high-grade EMC. Furthermore, numerous small nests with d-PAS and alcian blue-positive mucous cells predominated in about 5% of the whole tumor, and these mucous cells were encompassed by neoplastic myoepithelial cells. We should recognize this variant of EMC because we can't rule out the possibility of EMC even in the presence of mucous cells.
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sentani
authors.affiliation: Center of Oral Clinical Examination, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Ogawa
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Uraoka
authors.affiliation: Miyoshi Central Hospital, Hiroshima, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ikeda
authors.affiliation: Miyoshi Central Hospital, Hiroshima, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hayashi
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Hattori
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Yui
authors.initials: Y
authors.lastname: Hattori
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Naohide
authors.initials: N
authors.lastname: Oue
authors.affiliation: Department of Oral and Maxillofacial Pathobiology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Takata
authors.affiliation: Department of Molecular Pathology, Hiroshima University Institute of Biomedical and Health Sciences, Hiroshima, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Yasui
mesh_terms: D000368:Aged; D044963:Biopsy, Fine-Needle; D002454:Cell Differentiation; D005260:Female; D020397:Goblet Cells / Q000473:pathology; D006801:Humans; D009208:Myoepithelioma / Q000473:pathology* / Q000601:surgery; D009375:Neoplasms, Glandular and Epithelial / Q000473:pathology* / Q000601:surgery; D010306:Parotid Gland / Q000473:pathology / Q000601:surgery; D010307:Parotid Neoplasms / Q000473:pathology* / Q000601:surgery
keywords: epithelial-myoepithelial carcinoma; high-grade; mucous cell differentiation; parotid gland