Carcinosarcoma of the prostate: case report with molecular and histological characterization

Background: We report a case of prostatic carcinosarcoma, a rare variant of prostatic cancer, which is composed of a mixture of epithelial and mesenchymal components with a generally poor outcome. Aims and methods: We aim to identify molecular alterations, in particular copy number variations of AR and c-MYC genes, methylation and expression of glutathione S-transferase P1 (GSTP1), programmed death-ligand 1 (PD-L1), AR, and phosphorylated AR expression. Results: We found a distinct molecular pattern between adenocarcinoma and carcinosarcoma, which was characterized by high AR copy number variation gain; positive expression of PD-L1, AR, and phosphorylated AR; low espression of GSTP1 in epithelial component. The sarcomatoid component had a lower gain of the AR gene, and no expression of PD-L1, AR, phosphorylated AR, or GSTP1. Both components had a gain of c-MYC copy number variation. Conclusions: Our findings suggest that carcinosarcoma has specific molecular characteristics that could be indicative for early diagnosis and treatment selection.