Renal complications in patients with chronic lymphocytic leukemia (CLL) or monoclonal B lymphocytosis (MBL) are relatively common. However, the cause of renal failure in these patients is unclear. Unlike plasma cell dyscrasias, where a kidney biopsy is routinely performed for evaluation, renal biopsies are rarely performed in patients with CLL or MBL. As a result, little is known about the mechanisms causing renal abnormalities in these two diseases.
To better understand renal insufficiency, Mayo Clinic researchers reported the pathological findings and outcomes of a series of patients with CLL or MBL followed at the Mayo Clinic in Rochester, Minnesota, who underwent a kidney biopsy during the course of their disease. The study was published in the Haematologica journal.
“We had been seeing a number of patients with CLL or MBL develop kidney disease. We wanted to better understand the spectrum of renal lesions that can be seen in patients with CLL or MBL,” said Nelson Leung, M.D., nephrologist at Mayo Clinic, and co-author on this study.
Between 1995 and 2014, approximately 4,024 patients with CLL or MBL were cared for and monitored in Mayo Clinic’s Division of Hematology. Of those patients, 49 (1.2 percent) developed kidney disease and had a renal biopsy. The renal lesions were reviewed by a renal pathologist, and the clinical parameters were confirmed by a hematologist and a nephrologist.
Of the 49 patients whounderwent a renal biopsy, the most common pattern of injury was membranoproliferative glomerulonephritis (MPGN). Diseases in this category include proliferative glomerulonephritis with monoclonal immunoglobulin, cryoglobulinemic glomerulonephritis, immunotactoid glomerulonephritis, and fibrillary glomerulonephritis. Other common pathologies discovered were leukemic infiltration and minimal change disease (MCD).
“The results of our study show the variety of renal lesions associated with CLL or MBL is much greater than previously thought—with MPGN, CLL infiltration, and MCD as the three most common findings in patients with CLL or MBL and renal abnormalities,” said Dr. Leung.
These findings emphasize that renal abnormalities in patients with CLL or MBL may be more common than previously known,and CLL or MBL patients who develop renal insufficiency should receive a renal biopsy for further clarification.
“Our study indicates that clinical parameters by themselves are insufficient to make the diagnosis,” said Dr. Leung. “In order to correctly diagnose the kidney disease, a renal biopsy is required for CLL or MBL patients.”
The study also recommends all renal biopsies should be reviewed by an expert pathologist with individualization of the management plan formulated by CLL or MBL experts in collaboration with nephrologists.
“A renal biopsy may clarify the mechanism underlying the presence of renal insufficiency in patients with CLL/MBL and allow for more effective treatment,” added Dr. Leung.