title: Myoepithelioma of the soft palate: a case report giving special attention to the differential diagnosis.
abstract: BACKGROUND
  Myoepitheliomas are rare tumours that may generally arise from the minor or major salivary glands. The differential diagnosis of this tumour should be performed along with several benign and malignant soft tissue neoplasms. The present case report describes an asymptomatic mass that arose in the soft palate of 42 year old black woman with duration of the six months.
  
  
  METHODS
  An incisional biopsy of soft palate lesion was carried out and submitted for histological evaluation under the clinical hypothesis of salivary gland tumour. To confirm the myoepithelial nature of neoplastic cells the immunohistochemical reactions for smooth-muscle actin, cytokeratins and S100 were performed.
  
  
  RESULTS
  The histological examination revealed the presence of tumour originating from a minor salivary gland and covered by a stratified squamous oral epithelium. The tumour cells were arranged in order to form a myxoid pattern and, individually, small and/or medium spindle-shaped cells with predominantly round or ovoid nuclei, as well as epithelioid and plasmocytoid cells were noted. The stroma was myxomatous and no ductal or syringomatous epithelial structures were observed. Following the histological and immunohistochemical diagnosis of myoepithelioma, the lesion was surgically removed. After the surgery, a follow-up of one year showed no signs and symptoms of reccurrence.
  
  
  CONCLUSIONS
  The myoepithelioma should be carefully distinguished from the other soft tissue tumours, especially those arising from salivary glands, such as pleomorphic adenoma and adenoid-cystic carcinoma.
authors.affiliation: Department of Oral Pathology, School of Dentistry, University of São Paulo São Paulo Brazil.
authors.forename: Felipe Fornias
authors.initials: FF
authors.lastname: Sperandio
authors.affiliation: Department of Oral Pathology, School of Dentistry, University of São Paulo São Paulo Brazil.
authors.forename: Fernanda Salgueiredo
authors.initials: FS
authors.lastname: Giudice
authors.affiliation: Department of Oral Pathology, School of Dentistry, University of São Paulo São Paulo Brazil.
authors.forename: Décio Dos Santos
authors.initials: Ddos S
authors.lastname: Pinto-Junior
authors.affiliation: Department of Oral Pathology, School of Dentistry, University of São Paulo São Paulo Brazil.
authors.forename: Suzana Cantanhede Orsini Machado
authors.initials: SC
authors.lastname: de Sousa
keywords: differential diagnosis; minor salivary glands; myoepithelioma; palate; salivary gland diseases.; soft tissue neoplasms