32/1033 (3.1%) cases were MSI-H or dMMR (age: 39–85 years, median 64.5 years; 30 acinar, 1 ductal, and 1 small cell carcinoma; Gleason score 6–10; stage, N1 or M1; 21 mCRPCs, 67.7%); 7/32 (21.9%) carried pathogenic or likely pathogenic germline mutations in MMR genes (5 MSH2, 1 MSH6, 1 PMS2). This evidence concerns the gene MSH6 and small cell carcinoma.