title: Myoepithelioma of the parotid gland with extensive adipocytic metaplasia: Report of a case with intriguing aspects on fine needle aspiration and p63 immunohistochemical expression.
abstract: Myoepithelioma is a rare and usually benign salivary gland tumor derived from myoepithelial cells. Variability in cellular morphology and stromal composition leads to diagnostic pitfalls on fine-needle aspiration cytology; therefore, histology and immunohistochemistry are often required for definitive diagnosis. We describe a case of parotid gland myoepithelioma in a 76-year-old woman, which was discovered incidentally on cerebral magnetic resonance imaging. Fine-needle aspiration sampled cohesive aggregates of spindle-shaped cells embedded in a fibrillary matrix as well as abundant mature adipocytes, initially considered as part of normal salivary gland parenchyma. Histology of the resected specimen showed bundles of spindle-shaped cells embedded in loose connective tissue, admixed with numerous intralesional adipocytes. Immunohistochemical studies revealed a diffuse expression of p63 by this adipocytic population, an observation clearly indicating that myoepithelial cells can trans-differentiate and acquire the morphology of mature adipocytes. Knowledge of this phenomenon can be helpful in the work-up of salivary gland lesions. Diagn. Cytopathol. 2016;44:1090-1093. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Institute of Pathology, University Hospital, Lausanne, Switzerland.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Schneider
authors.affiliation: Institute of Pathology, University Hospital, Lausanne, Switzerland.
authors.forename: Antoine
authors.initials: A
authors.lastname: Nobile
authors.affiliation: Medical Imaging Caroline, Lausanne, Switzerland.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Duvoisin
authors.affiliation: Institute of Pathology, University Hospital, Lausanne, Switzerland.
authors.forename: Chiara
authors.initials: C
authors.lastname: Saglietti
authors.affiliation: Institute of Pathology, University Hospital, Lausanne, Switzerland.
authors.forename: Massimo
authors.initials: M
authors.lastname: Bongiovanni
mesh_terms: D017667:Adipocytes / Q000378:metabolism / Q000473:pathology*; D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D044963:Biopsy, Fine-Needle; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008679:Metaplasia; D009208:Myoepithelioma / Q000378:metabolism / Q000473:pathology*; D010307:Parotid Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; C081876:CKAP4 protein, human; D008565:Membrane Proteins
keywords: FNA; adipocytic differentiation; myoepithelial cells; myoepithelioma; p63; salivary gland neoplasm