Case Presentation: A 72 yo female with a past medical history of HTN, DM2, and CKD III (baseline creatinine of 1.1) was admitted to our hospital for mild vaginal bleeding and acute kidney injury.  Over the preceding two months she had been seen by nephrology as an outpatient for worsening hypertension, edema, and proteinuria. During that evaluation, she denied use of nonsteroidal anti-inflammatories, her creatinine was 1.9, BP 185/88, and she had pitting edema.  Labs were negative for complement levels, ANA, and c-ANCA/p-ANCA IgG. Her random urine protein was >2000mg/dL compared to a baseline level of 5mg/dL four years prior. Inpatient work up demonstrated a creatinine of 5.5, urine eosinophil level of 7%, SPEP without evidence of monoclonal proteins, and a 24-hour urine collection of >23g/day. Renal biopsy was performed and demonstrated proliferative glomerulonephritis with monoclonal IgG deposits.  The patient was treated with prednisone and her creatinine initially improved to 2.3. However, she subsequently deteriorated with decreased urine output, creatinine of 7.2 and BUN of 100, as well as worsening blood pressure control, leading to need for hemodialysis. Further work up included a negative endometrial biopsy, negative hepatitis B/C panel, and a bone marrow biopsy negative for malignancy.

Discussion: Dysproteinemias that result in proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) are a rare and poorly understood entity caused by monoclonal deposition of IgG, which mimics immune-complex glomerulonephritis. This condition was initially recognized in 2004. In 2009 Nars et al. reported the largest case series of PGNMID patients in which 37 patients were retrospectively identified and reviewed.  In this study, 81% were white, 62% female, and 65% older than 50 years of age. On 30 month follow up of 32 of the patients, 38% had complete or partial recovery, 38% had persistent renal dysfunction, and 22% progressed to ESRD. Treatment strategies included; no treatment, renin angiotensin system (RAS) blockade alone, or immunomodulatory therapy with prednisone alone or in combination with RAS blockade. There was no statistical benefit to any treatment modality. None of the above patients were noted to develop hematologic malignancy on follow up, for which it was concluded that PGNMID does not appear to be a precursor of myeloma in the vast majority of patients, unlike other dysproteinemia-related renal diseases. To our knowledge, there has been no prospective, multicenter, controlled study of a larger cohort of patients with PGNMID to determine the optimal therapeutic regimen for these patients.

Conclusions: Patients with rapidly progressive renal disease presenting with nephrotic syndrome characteristics need an evaluation via renal biopsy. Uncommonly, proliferative glomerulonephritis with monoclonal IgG deposits may be identified, and further research is needed to clarify an optimal treatment strategy.