[A case report of light and heavy chain deposition disease (IgG2 lambda)]

Area of Science:

• Nephrology
• Hematology
• Immunology

Background:

• A 73-year-old male presented with hypertension, proteinuria, and edema, with a history of interstitial pneumonia.
• Laboratory findings revealed renal dysfunction, anemia, and elevated IgG2 levels, alongside M-protein and Bence Jones protein (lambda type).

Observation:

• Renal biopsy showed mesangial proliferation, nodular glomerulonephritis, and deposition of PAS-positive, Congo red-negative material.
• Immunofluorescence confirmed IgG and lambda light chain deposition along glomerular and tubular basement membranes and in the mesangium.
• Electron microscopy revealed electron-dense deposits and microfibrillar structures (14 nm) in the mesangium.

Findings:

• The patient was diagnosed with plasma cell dyscrasia.
• Renal pathology demonstrated features consistent with immune complex deposition, specifically IgG lambda light chains.
• The presence of IgG2 and lambda light chain restriction in both serum and kidney tissue suggests a monoclonal gammopathy-related nephropathy.

Implications:

• This case underscores the importance of investigating plasma cell dyscrasias in patients with unexplained renal abnormalities.
• Understanding the specific immunoglobulin deposition patterns can aid in diagnosing and potentially managing such renal complications.
• Further research into the role of IgG2 and lambda light chains in kidney disease is warranted.