Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution.

BACKGROUND AND OBJECTIVES To better define the clinical-pathologic spectrum and prognosis of monoclonal immunoglobulin deposition disease (MIDD), this study reports the largest series. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Characteristics of 64 MIDD patients who were seen at Mayo Clinic are provided. RESULTS Of 64 patients with MIDD, 51 had light chain deposition disease, 7 had heavy chain deposition disease, and 6 had light and heavy chain deposition disease. The mean age at diagnosis was 56 years, and 23 patients (36%) were ≤50 years of age. Clinical evidence of dysproteinemia was present in 62 patients (97%), including multiple myeloma in 38 (59%). M-spike was detected on serum protein electrophoresis in 47 (73%). Serum free light chain ratio was abnormal in all 51 patients tested. Presentation included renal insufficiency, proteinuria, hematuria, and hypertension. Nodular mesangial sclerosis was seen in 39 patients (61%). During a median of 25 months of follow-up (range, 1-140) in 56 patients, 32 (57%) had stable/improved renal function, 2 (4%) had worsening renal function, and 22 (39%) progressed to ESRD. The mean renal and patient survivals were 64 and 90 months, respectively. The disease recurred in three of four patients who received a kidney transplant. CONCLUSIONS Patients with MIDD generally present at a younger age than those with light chain amyloidosis or light chain cast nephropathy. Serum free light chain ratio is abnormal in all MIDD patients, whereas only three-quarters have abnormal serum protein electrophoresis. The prognosis for MIDD is improving compared with historical controls, likely reflecting earlier detection and improved therapies.