Kidney Week

Abstract: TH-PO0546

The Great Masquerade: Beyond Textbook Seronegative Immune Complex Glomerulopathy

Session Information

• Glomerular Diseases: IgAN, IgA Vasculitis, and More
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

• Naing, Kyaw Moe, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Kyaw Moe Naing, MBBS

• Oldford, Elaine J., VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Elaine J. Oldford, MD

• Gardezi, Lemar Ahmad, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Lemar Ahmad Gardezi, MD

• Rayas, Jose Luis, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Jose Luis Rayas, MD

• Kent, Devon Gerard, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Devon Gerard Kent, DO

• Al-adroos, Hira H., VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Hira H. Al-adroos, DO

• Sumida, Keiichi, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Keiichi Sumida, MD, PhD, MPH, FASN

• Sharma, Shilpa, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Shilpa Sharma, MD, MPH

• Rhee, Connie, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Connie Rhee, MD, MS

• Siu, Man Kit Michael, VA Greater Los Angeles Healthcare System, Los Angeles, California, United States

Man Kit Michael Siu, MD, MS

Introduction

Proteinuria in elderly diabetics is often attributed to diabetic nephropathy (DN). However, abrupt nephrotic syndrome and absence of retinopathy should raise suspicion for non-diabetic kidney disease (NDKD). We report an atypical seronegative immune complex glomerulopathy with fibrillary features responsive to immunosuppression despite incomplete diagnostic classification.

Case Description

A 78-year-old man with longstanding, well-controlled T2DM without retinopathy presented with one month of anasarca after a recent uppre respiratory infection. Evaluation showed albumin 1.7 g/dL and proteinuria 26.5 g/day. Serologies (anti-PLA2R, ANA, ANCA, viral, paraproteinemia) and complements were normal.

Kidney biopsy demonstrated nodular diabetic glomerulosclerosis with immune complex injury. IF showed granular IgG/C3 staining. EM demonstrated subepithelial deposits and mesangial fibrils (12.4–16.4 nm). DNAJB9 staining was negative, arguing against classic fibrillary glomerulonephritis. Congo red staining was positive for ALECT2 amyloid. Findings were unclassifiable.

Despite 40–50% IFTA, nephrotic syndrome prompted treatment with RAAS blockade, rituximab (1 g ×2), and corticosteroid taper. Proteinuria improved 71.7% (26.5 g/day to 7.5 g/day) with stable renal function.

Discussion

This case highlights the complexity of overlapping diabetic and unclassified immune complex pathology. Response to B-cell depletion supported a treatable immune-mediated driver beyond diabetic nephropathy. In cases with clinical red flags, empiric therapy may be justified despite diagnostic uncertainty.

Figure 1:
(A) Light microscopy: Nodular mesangial expansion consistent with diabetic glomerulosclerosis.
(B) Immunofluorescence: Granular capillary loop IgG staining supporting immune complex injury.
(C) Electron microscopy: Mesangial fibrils measuring 12.4–16.4 nm with associated subepithelial deposits.
(D) Congo red-positive ALECT2 amyloid deposition.