Myoepithelial tumours of skin and soft tissue: an update

Over the past decade, myoepithelial neoplasms have been recognized to arise primarily in skin and soft tissue. Similar to their salivary gland counterparts, owing to the plasticity of myoepithelial cells, these tumours show considerable cytological and architectural heterogeneity. Recognition of these uncommon neoplasms can be challenging, and a broad differential diagnosis may be considered. Criteria for malignancy in myoepithelial tumours of soft tissue have recently been established and are essentially cytological in nature, in contrast to the criteria used in salivary gland neoplasms. Myoepithelial carcinomas of soft tissue appear to be overrepresented in the paediatric population, in whom an aggressive clinical course is common. Whereas some cutaneous myoepitheliomas are similar to those in soft tissue, a distinctive ‘syncytial variant’ comprises at least 50% of dermal cases. This review will examine the pathological features, clinical behaviour and differential diagnosis of myoepithelial tumours of skin and soft tissue.