A liver biopsy was obtained and pathology revealed metastatic disease most consistent with small-cell carcinoma with immunohistochemistry that was diffusely positive for INSM1, synaptophysin, MOC-31, and TTF-1 and focally positive for chromogranin, and Ki-67 labeling index was > 90%; staining was negative for PSA, NKX3.1, CDX2, PAX8, and GATA-3 (Figure 3). This evidence concerns the gene KLK3 and small cell carcinoma.