Bladder Involvement of Diffuse Large B-cell Lymphoma Diagnosed by a Cytological Study of the Urine

The diagnosis of lymphoma involvement from the urine sediment has been rarely reported in the literature. We present a 78-year-old woman with diffuse large B-cell lymphoma in whom a relapse of the disease was diagnosed due to the presence of lymphoma cells in the urine. The analysis of urine by flow cytometry demonstrated a clonal B-cell origin, with an identical immunophenotype to that of the initial lymphoma. This case emphasizes the interest of cytological studies of the urine in cases with suspected bladder involvement by lymphoma.