Urothelial Carcinoma : Vascular Invasion
High-grade urothelial carcinoma within a vessel in a radical cystectomy specimen. The nest conforms to the shape of the vessel. Endothelium is clearly visible. There are two diagnostic pitfalls that can lead to overdiagnosis of vascular invasion: 1) carryover of tumor fragments on the knife edge and their deposition within vessels simulating vascular invasion; 2) retraction artifact around tumor clusters creating the appearance of a vessel with tumor.