Myeloperoxidase anti-cytoplasmic antibody related crescentic glomerulonephritis in a patient with IgG3λ monoclonal immunoglobulin deposition disease with membranous features

Acute renal failure in a patient with PR3-ANCA and monoclonal immunoglobulin deposition disease: Case report

RATIONALE

Acute renal failure developing over a short period of time with evidence of glomerular disease by urine sediment microscopy characterizes the clinical syndrome of rapidly progressive glomerulonephritis (RPGN), of which the most common causes are ANCA-associated glomerulonephritis (GN), immune-complex mediated GN and anti-GBM disease.

PATIENT CONCERNS

This was a middle-aged gentleman who presented with acute renal failure and a positive PR3-ANCA.

DIAGNOSIS

Renal biopsy showed an unusual combination of PR3-ANCA GN with focal crescents, monoclonal immunoglobulin deposition disease (MIDD) and mesangial IgA deposition on renal biopsy.

INTERVENTIONS

Serum and urine protein electrophoresis (UPEP) and immunofixation showed no detectable monoclonal paraprotein; bone marrow biopsy was negative for plasma cell neoplasia. He received high dose steroids and rituximab.

OUTCOMES

The patient did not respond to treatment and progressed to end-stage renal failure within 2 months after presentation.

LESSONS

To our knowledge, the simultaneous occurrence of MIDD, PR3-ANCA and mesangial IgA has not been reported. This case highlights not only the diagnostic but also the therapeutic challenges that such a complex case presentation poses to clinicians, where the culprit may not always be what would seem most obvious (such as ANCA in a patient with RPGN) but may, in fact, be an underlying and unsuspected disease, or possibly a combination of both.

An IgA1-lambda-type monoclonal immunoglobulin deposition disease associated with membranous features in a patient with IgG4-related kidney disease: a case report

BACKGROUND

IgG4-related disease (IgG4-RD) is a newly recognized fibroinflammatory condition. The kidney is one of the organs commonly affected by IgG4-RD. Tubulointerstitial nephritis (TIN) is the main feature, and membranous nephropathy (MN) has also been described frequently. In MN, polyclonal immunoglobulins and complements are deposited in granular form along the glomerular basement membranes (GBMs). Unusual cases of monoclonal immunoglobulin deposition disease (MIDD) associated with membranous features have been reported. MIDD is morphologically similar to MN but contains immunoglobulins considered to be derived from single B-cell clone.

CASE PRESENTATION

We describe a 65-year-old man who was referred to our hospital because of hyperproteinaemia, eosinophilia, anaemia, and proteinuria. A renal biopsy demonstrated infiltration of plasma cells and eosinophils in the interstitium, and the ratio of IgG4-positive plasma cells to IgG-positive plasma cells was 55%. The patient was diagnosed as having IgG4-related TIN. Periodic acid methenamine silver staining under light microscopy revealed a bubbling appearance and spike formation in the GBM. On immunofluorescence, the expression of IgG and complements was negative; however, IgA was positively expressed in a granular pattern along the GBM. An IgA subclass analysis revealed a significant deposition of IgA1-lambda (IgA1-λ). Electron microscopy revealed irregular and small non-organized and non-Randall-type granular electron-dense deposits in the GBM that were shaped like snow leopard spots.

CONCLUSIONS

After corticosteroid therapy was initiated, the patient's eosinophilia remarkably improved and his serum creatinine, IgG, and IgG4 levels decreased to within the normal ranges. However, massive proteinuria persisted. To our knowledge, this is the first reported case of IgG4-related TIN associated with IgA1-λ-type MIDD with membranous features.