Introduction:
Monoclonal gammopathy of renal significance (MGRS) encompasses a spectrum of disorders characterized by kidney damage due to deposition of monoclonal immunoglobulins produced by non-malignant or premalignant B cell or plasma cell clones. Proliferative glomerulonephritis with monoclonal immunoglobulin G deposits (PGNMID) is rare, identified in only 0.07-0.17% of kidney biopsies. Unlike other forms of MGRS, detecting circulating clones in PGNMID is more challenging, leading to a higher likelihood of being overlooked or misdiagnosed during clinical evaluation.
Methods:
Case summary:
A 61-year-old male with past history of pituitary prolactinoma maintained on Cabergoline presented with acute kidney injury and history of 60 pounds weight gain over the duration of 2 months. Medical history dates back to 1.5 years prior to presentation, when he was found to have abnormal kidney function with severe proteinuria. A renal biopsy done at an outside hospital was suggestive for membranous nephropathy. Patient was managed supportively with angiotensin-receptor blocker and diuretics. However, his kidney function continued to worsen, presenting with a creatinine of 2.78, up from a baseline of 1.7, and peaking at 5.19. Due to worsening kidney function and diuretics resistant hypervolemia, he was started on renal replacement therapy. A work-up done was significant for nephrotic range proteinuria, glucosuria and hematuria.
Further work-up, including a kidney biopsy, reveled PGNMID, consistent with MGRS. Bone marrow biopsy showed immunostaining 10-15% CD138+ plasma cells. Following discussion among Nephrology and Oncology teams, the patient was started on Cyclophosphamide-Bortezomib-Dexamethasone (CyBorD) therapy for MGRS. Two day later, his creatinine started trending down, and no further dialysis was indicated.
Results:
Conclusions:
This case highlights the complexity and diagnostic challenges associated with PGNMID. Despite its rarity and difficulty in detecting circulating clones, early recognition and appropriate management are crucial for improving renal outcomes. It is distinctly possible that his previous diagnosis of membranous glomerulonephritis was PGNMID all along.
In this patient, timely initiation of renal replacement therapy, CyBorD therapy, and immunosuppressive treatment led to a stabilization of kidney function. Ongoing follow-up is essential for monitoring disease progression and ensuring optimal long-term management.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.