An extensive IHC workup was performed and was unrevealing with negative staining for carcinoma (CAM5.2, pancytokeratin, CK7, CK20), melanoma (S100, SOX10, HMB-45, Melan-A), hematolymphoid markers (CD45, CD43, CD3, CD20, CD30, CD4), myeloid markers (CD34, CD117), myoid markers (SMA, desmin), neuroendocrine markers (CD56, synaptophysin, chromogranin, NSE), pDC markers (CD123, CD303), histiocytic markers (CD68, CD163, CD1a, langerin), and follicular dendritic cell marker (CD21). The gene discussed is SOX10; the disease is melanoma.