Nek9,A Sensitive Immunohistochemical Marker For Schwannian, Melanocytic And Myogenic Tumours

AimsIn our previous study, striking Nek9 staining was observed in peripheral nerves for the first time. Therefore, in the current study, we aimed to detect Nek9 expression in peripheral nerve sheath tumours, melanocytic tumours and their mimics.MethodsThe expression of Nek9 was analysed in 234 mesenchymal tumours including schwannoma, neurofibroma, malignant peripheral nerve sheath tumour (MPNST), melanoma and their mimics adopting immunohistochemistry. In addition, S-100 and SOX10 were detected in all tumours.ResultsThe results revealed an intense and diffuse staining of Nek9 in all schwannomas (30/30) and melanomas (20/20). The neurofibromas (86%, 19/22) and MPNSTs (76%, 18/21) showed a high frequency of positive Nek9 staining. Nek9 showed a comparable sensitivity to S-100, and better sensitivity and less specificity than that of SOX10. Among the histological mimics, Nek9 was only strongly and diffusely expressed in rhabdomyosarcomas (RSs) (97%,37/38) while negatively stained in most of the other tumours. It was noted that Nek9 immunoresponse was more diffuse than that of MyoD1 and myogenin in RS.ConclusionsIn summary, Nek9 has a good sensitivity in the diagnosis of tumours with Schwannian, melanocytic and skeletal muscle differentiations. The immunohistochemical analysis of Nek9 expression may be helpful in the diagnosis and differential diagnosis of the aforementioned tumours.