Large cell neuroendocrine tumor of the urinary bladder is very rare. It is a type of neuroendocrine carcinoma that is morphologically different from small cell carcinoma.

This manuscript describes a 67-year-old man who presented with hematuria. Ultrasonogrophic and computer tomography revealed a 5 cm mass in right posterolateral wall of the bladder that invaded perivesical tissue and he subsequently underwent transurethral resection. Microscopic examination showed a tumor with a sheet-like and trabecular growth pattern comprising necrotic areas which infiltrated the muscularis propria. Tumoral cells had coarse chromatin, prominent nucleoli, moderate amount of cytoplasm and immunohistochemically stained strongly positive with synaptophysin, chromogranin and CD56.

There are only few case reports of large cell neuroendocrine tumor of the urinary bladder so the biological behavior and the treatment protocol of these tumors are still obscure. Appropriate management protocols and prognostic estimation could be achived by the increased number of cases being reported. Therefore in a case of a poorly differentiated tumor in bladder, although rare, it is important to consider large cell neuroendocrine carcinoma in differential diagnosis.