Department of Medical Oncology, Ioannina University Hospital, Niarxou Avenue, 45500 Ioannina, Greece.
Urine cytology has been a useful tool for the diagnosis of urinary tract malignancies. However, the presence of tumor cells in the urine sediment without an obvious urothelial metastatic deposit is a rare phenomenon and in patients with lung cancer has never been reported. We present five cases with metastatic lung cancer and positive urine cytology. The possible mechanisms underlining this phenomenon and its implications are discussed.