I am sorry about your mom. We are not med. doctors here. So my guess is white patches can be necrotic tissue from uti. That does not mean that they are cancer. Hopefully she stays cancer free after beating the leukemia.
66yo female, 1992-Non-Hodg. lymphoma(NHL) high grade, chemo, rads, 2007 NHL, low grade, rads, 2013 NHL low grade, stage 4, chemo till Jan 2015; 2014 TCC, first Turb 01/29/2015.