Synchronous solitary metastasis of transitional cell carcinoma of the bladder to the testis.

Primary tumors known to metastasize to the testis, in order of decreasing frequency, are prostate, lung, gastrointestinal tract, melanoma, and kidney tumors. Metastasis from bladder cancer to the testis is extremely rare, occurs with advanced and metastatic disease, and is usually a finding at autopsy. We report a rare, and probably the first, case of solitary and synchronous metastatic transitional cell carcinoma of the bladder to the testis, discovered on the preoperative workup. An incidentally discovered testicular mass in a man with high-grade, invasive bladder cancer should be considered a metastatic lesion until proven otherwise.