Plasmacytoid Urothelial (Transitional Cell) Carcinoma
Differential Diagnosis
- The prinicpal differential diagnosis is plasmacytoma
- Usually, awareness of this pattern is enough to permit a diagnosis but stains can be useful if necessary
- P63 and strong keratin indicate carcinoma
- Plasma cell processes may sometimes show weak keratin staining
- Kappa/lambda in situ hybridization or IPOX will identify nearly all plasmacytomas
- MUM1 preferentially stains plasmacytoma
- CD138 is expressed on many carcinomas and is not useful
