The type of lymphocyte infiltration near urothelial carcinoma is diagnostic for chronic lymphocytic leukemia.

T-lymphocytic infiltration near the tumor site is an expected immune response in bladder cancers. However, reports of patients with bladder cancer exhibiting small lymphocytic infiltration of the bladder tissue are very rare in the literature. Here, the patient was presented to our group with hematuria, but subsequently diagnosed as exhibiting invasive bladder cancer and chronic lymphocytic leukemia with suspicious lymphocytic infiltration in a transurethral resection specimen. This case emphasizes the importance of lymphocytic infiltration's nature near urothelial carcinoma.