Background: SOX-10 expression can be demonstrated by immunohistochemistry in salivary gland myoepitheliomas, but its expression in cutaneous myoepitheliomas and in cutaneous mixed tumors with prominent myoepithelial cells has not been studied.
Methods: We assessed the staining pattern of SOX-10 in five cutaneous myoepitheliomas and six cutaneous mixed tumors with a prominent myoepithelial component among both the myoepithelial cells and cells lining lumens. In addition, we examined the staining of S100, microphthalmia-associated transcription factor (MiTF), keratin cocktail, HMK903, smooth muscle actin (SMA) and epithelial membrane antigen (EMA).
Results: SOX-10 positivity was seen in three of five (60%) cutaneous myoepitheliomas and in the myoepithelial cells of all cutaneous mixed tumors. SOX-10 expression on the cells lining the glandular structures in mixed tumors was variable. All myoepitheliomas and mixed tumors stained positively with S100 and negatively with MiTF. Pan-keratin, HMK903, SMA and EMA showed variable expression.
Conclusions: SOX-10 is a relatively reliable marker for staining cutaneous myoepitheliomas. Cutaneous myoepitheliomas are notoriously difficult to diagnose, and the addition of SOX-10 to the repertoire of stains that can label this tumor is of practical utility. These results further support that cutaneous myoepitheliomas and cutaneous mixed tumors exist on a morphologic and immunophenotypic spectrum.
Keywords: adnexal neoplasm; cutaneous adnexal neoplasms; cutaneous neoplasm; dermatopathology; immunocytochemistry.
© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.