A 50 y.o. patient was admitted to the hospital with complaints of blood in urine. There was no pain or urination disorders, hematuria has lasted for 3 days. Objectively: kidneys are not palpable, suprapubic region has no pecularities, external genitals have no pathology. Rectal examination revealed: prevesical gland is not enlarged. Cytoscopy revealed no changes. What disease would you think about first of all?