Salivary-type myxoid myoepithelioma of the sinonasal tract: a potential diagnostic pitfall.

A 38-year-old woman presented with otalgia and facial pain. She was found to have a tumour involving the right maxillary sinus and pterygopalatine fossa. Exclusively composed of a myxoid population of spindle and stellate cells within a mucosubstance-rich matrix, it was originally interpreted as a mesenchymal neoplasm. However, immunophenotypic characterization revealed a pure population of salivary-type myoepithelial cells with cytoplasmic co-expression of cytokeratin, vimentin, muscle-specific actin, S-100 protein and glial fibrillary acidic protein. Sinonasal myxoid myoepithelial neoplasia is exceedingly rare and represents a potential diagnostic pitfall.