Osseous metaplasia within a urothelial bladder cancer nodal metastasis: a case report.

Background: Osseous metaplasia within bladder cancer is extremely rare and, to our knowledge, has not been previously reported within a urothelial bladder carcinoma (UBC) nodal metastasis.

Case: A 78-year-old man underwent radical cystoprostatectomy because of high-grade pT2 UBC. Pathology revealed a high-grade pT4aN2 UBC with osseous metaplasia into a massively metastatic lymph node but not into the primary bladder tumor.

Conclusion: Based independently on its location, this finding warrants a careful differential diagnosis with sarcomatoid bladder tumors and is likely to be a marker of tumor aggressiveness, thus recommending aggressive treatment.