Stromal osseous metaplasia in urothelial carcinoma of the bladder: An unusual and challenging feature. A case report / Carcinoma urotelial de vejiga con metaplasia ósea estromal: una característica inusual y desafiante. Presentación de un caso

A 62-year-old male presented with pain and haematuria starting 3 months before. The computed tomography showed focal and mural bladder thickening with ureteropelvic dilatation. The following transurethral bladder resection revealed a high-grade muscle-invasive urothelial carcinoma. In the subsequent cystoprostatectomy we found the same tumour, but adding focal tumour-associated stromal osseous metaplasia. Ossifying metaplasia is an extremely rare feature in urothelial carcinoma, with a few reported cases and represents a diagnostic challenge, mimicking radiotherapy-induced sarcoma or sarcomatoid carcinoma. (AU)

Varón de 62 años que consulta por dolor y hematuria desde hace 3 meses. En la tomografía computarizada se observó un engrosamiento focal y mural de la vejiga con dilatación ureteropélvica. La resección vesical transuretral reveló un carcinoma urotelial infiltrante de alto grado músculo-invasivo. En la cistoprostatectomía posterior encontramos el mismo tumor, pero añadiendo focos de metaplasia ósea estromal asociada al tumor. La metaplasia osificante es una característica extremadamente rara en el carcinoma urotelial, con algunos casos informados, y representa un desafío diagnóstico, ya que simula un sarcoma inducido por radioterapia o un carcinoma sarcomatoide. (AU)

Stromal osseous metaplasia in urothelial carcinoma of the bladder: An unusual and challenging feature. A case report.

A 62-year-old male presented with pain and haematuria starting 3 months before. The computed tomography showed focal and mural bladder thickening with ureteropelvic dilatation. The following transurethral bladder resection revealed a high-grade muscle-invasive urothelial carcinoma. In the subsequent cystoprostatectomy we found the same tumour, but adding focal tumour-associated stromal osseous metaplasia. Ossifying metaplasia is an extremely rare feature in urothelial carcinoma, with a few reported cases and represents a diagnostic challenge, mimicking radiotherapy-induced sarcoma or sarcomatoid carcinoma.