A “double-seropositive” Vasculitis for antiglomerular basement membrane antibodies and antineutrophil cytoplasmic antibody, and multiple myeloma, all three with simultaneous diagnosis of renal involvement, common pathophysiology, or pure coincidence? first case in the World

Emergence of proteinase 3-antineutrophil cytoplasmic antibody-associated glomerulonephritis with mesangial immune deposition during the clinical course of IgG λ monoclonal gammopathy of uncertain significance

Patients with monoclonal gammopathy of uncertain significance (MGUS) is sometimes associated with renal diseases, usually due to the deposition of secreted monoclonal immunoglobulin or a fragment thereof, a condition which is defined as monoclonal gammopathy of renal significance. Patients with MGUS appear to be at increased risk for various autoimmune conditions. We report the case of a 68-year-old man developed nephritic syndrome and mild renal insufficiency during the course of IgG λ MGUS. Laboratory findings showed hypocomplementemia, cryoglobulinemia, proteinase 3-antineutrophil cytoplasmic antibody (PR3-ANCA) positivity and monoclonal proteins (λ light chain and λ-Bence-Jones protein) in the urine. A kidney biopsy revealed crescentic glomerulonephritis with mesangial immune deposits without paraproteins. Treatment with prednisolone for ANCA-associated glomerulonephritis, normalized urinalysis and decreased PR3-ANCA but MGUS persisted. This is a rare case of PR3-ANCA-associated glomerulonephritis with comorbid IgG λ MGUS with various pathological paraproteins. We highlight it as a clinical example with diagnostic and therapeutic implications.

ANCA and anti-glomerular basement membrane double-positive patients: A systematic review of the literature

INTRODUCTION

Double-positive patients (DPP) exhibiting anti-glomerular basement membrane (GBM) and anti-neutrophil cytoplasmic antibodies (ANCAs) belong to an entity that is newly and poorly described, mainly in short series. We aimed to better characterize the epidemiological features, clinical presentation and therapeutic outcomes of these patients through a systematic review.

METHODS

We performed a systematic review of English-, German-, Spanish- and French-written publications from February 1987 to March 2020 reporting cases of DPP using the following databases: PubMed, Scielo, ScienceDirect, Google Scholar, The Cochrane Library, Open Grey, The Grey Literature Report, Clinicaltrials.gov and International Clinical Trial Registry Platform of the World Health Organization.

RESULTS

In total, 538 DPP were identified from 90 articles. Their clinical presentations were often severe, and the majority exhibited acute kidney failure (91.8%) with a median initial serum creatinine level of 873 μmol/L; 50.7% had alveolar haemorrhage. Other manifestations were present in 30.3% of DPP, mainly ear, nose, throat and articular manifestations. ANCAs were predominantly directed against MPO (n = 377/523; 72.1%) compared to PR3 (n = 107/523; 20.5%), with rare cases of triple positivity (n = 15/538; 2.9%). Although most patients received initial immunosuppressive therapy (n = 285/317; 89.9%), the one-year overall, renal and relapse-free survival rates were 64.8%, 38.7% and 71.1%, respectively.

CONCLUSION

DPP are associated with the characteristics of two eponymous vasculitis types, responsible for a poor overall and renal prognosis. Thus, simultaneous testing of both antibodies and systematic renal biopsy should be recommended in every patient with rapidly progressive glomerulonephritis to recognize this difficult-to-treat and rare disease.