BACKGROUND: Neuroendocrine carcinomas (NECs) of the urological organs are observed occasionally, although simultaneous development in the kidney and blabber has not been reported.

CASE REPORT: We report a case of a metastatic NEC of the kidney and bladder in a 77-year-old woman who underwent renal biopsy and transurethral resection of the bladder tumor. Pathological examination revealed NEC in the kidney and the bladder samples. Immunohistochemical examination revealed strongly positive staining for synaptophysin, chromogranin A, and CD56, and focally positive staining for cytokeratin AE 1/3 and Cam 5.2. Fluorescence in situ hybridization confirmed the increased chromosome 3 copy number, and loss of hybridization in 3q21, 5q22-23, 10q26, and 13q14 was detected when the tumor samples were compared with normal samples.

CONCLUSIONS: This is a rare case of NEC-specific genetic abnormalities in a kidney-derived tumor, and is the first report to identify kidney-derived NEC that metastasized to the bladder via the urinary tract.

Keywords: Chromosomes, Human, Pair 3 - genetics, Carcinoma, Neuroendocrine - secondary, Kidney Neoplasms - pathology, Loss of Heterozygosity - genetics, Urinary Bladder Neoplasms - secondary