Negative staining for a broad panel of other markers – including cytokeratin 20 (CK20), GATA-3, special AT-rich sequence-binding protein 2 (SATB2), paired-box gene 8 (PAX8), SRY-box transcription factor 17 (SOX17), synaptophysin, chromogranin, hepatocyte paraffin 1 (HepPar-1), arginase, and human melanoma black 45 (HMB-45), further excluded neoplasms from other common primary sites. The gene discussed is KRT20; the disease is melanoma.