RESUMEN
Among neuroendocrine tumors of the urinary bladder, small cell carcinoma (SCCB) is the most common one. Less frequent is carcinoid tumour and very rare is a large-cell neuroendocrine carcinoma. Small cell neuroendocrine carcinoma is a very aggressive tumour, with major frequency in the seventh decade. In 95% of patients it presents with hematuria and muscle invasive disease. A case of a patient with the urinary bladder tumour, which had muscle invasion and extension in perivesical tissue, was presented. The patient was diagnosed with combined form of the tumour, consisting of small cell and squamous cell patterns. Some of the imunochistochemical markers used in diagnosis were chromogranin A, synaptophysin, cytokeratins, LCA and Ki-67. Consequently, neuroendocrine differentiation of small cell patterns of the tumour was proven. Neoadjuvant cisplatin- based chemotherapy followed by radical resection should be considered as the treatment of choice in surgically resectabile SCCB. Because of that it is essential to make histopathologic diagnosis of SCCB in transuretral tumour samples using, chromogranin A or synapthysin.