Diagnosis: Granulomatosis with Polyangiitis (GPA, formerly Wegener’s disease)
Great learning case! Let’s break it down, starting from the HPI. We meet a 40 year-old woman with acute on chronic respiratory symptoms and a purpuric rash with toe ischemia. Our broad differential includes an inflammatory, vasculitic, or embolic process. Initial laboratory assessment is notable for acute kidney injury with sub-nephrotic range proteinuria, hematuria, and red blood cell casts on urine microscopy. Together, this suggests an acute nephritic syndrome and a rapidly progressive glomerulonephritis (RPGN).
With our working differential for RPGN, we now utilize serologic testing and ultimately the kidney biopsy to make the diagnosis. In this case we find normal complement levels, normal ANA, anti-double stranded DNA, and undetectable cryoglobulins – these data make immune-complex mediated disease less likely. also make. Thus, we are left with RPGN that is either pauci-immune or anti-GBM disease.
In a patient with RPGN, strongly positive c-ANCA titers (antibody against proteinase-with a cytoplasmic staining pattern) on the background of sinusitis and epistaxis lead us towards ANCA-associated vasculitis. C-ANCA is more commonly associated with Granulomatosis with Polyangiitis (GPA). What about that other ANCA? The presence of p-ANCA (antibody against myeloperoxidase with a perinuclear staining pattern) is more commonly associated with eosinophilic granulomatosis with polyangiitis and microscopic polyangiitis.
If our diagnosis is correct, histology show us crescentic necrotizing glomerulonephritis and medullary angiitis– which it does! We also see obliteration of the capillary loops and endothelial cell proliferation. Neutrophils are also visible within the capillary loops and in the medullary interstitial space. The clincher for this diagnosis is the negative immunofluorescence (IF). We don’t get the electron microscopy (EM) for this case, but we would not expect to see any deposits.
The clinical presentation of GPA is diverse, but classic findings include upper respiratory tract symptoms, epistaxis, hemoptysis (due to diffuse alveoloar hemorrhage), and rapidly progressive renal failure (think: pulmonary-renal syndrome). Leukocytoclastic vasculitis in the skin can be seen as well. Although GPA is associated with “pauci-immune” lesions at the level of the glomerulus, detection of immune deposits in early skin lesions can be seen with active disease.
Treatment for GPA: induction cyclophosphamide (IV or oral, CYCLOPS trial) or Rituximab (RAVE, RITUXVAS trials: rituxmab noninferior to CYC) with glucocorticoids. First choice for maintenance therapy remains azathioprine (CYCAZAREM trial). Diffuse pulmonary hemorrhage is an indication for plasmapheresis in combination with induction therapy, though the benefit of plasma exchange continues to be reassessed in on-going trials. Don’t forget the new kid on the block, avacopan, the C5a receptor antagonist that has shown some efficacy and potential to decrease steroid dosing.
Check out these references for more:
- Jennette JC, Nachman PH: ANCA Glomerulonephritis and Vasculitis. Clin. J. Am. Soc. Nephrol. CJASN 12: 1680–1691, 2017
- Schönermarck U, Gross WL, Groot K de: Treatment of ANCA-associated vasculitis. Nat. Rev. Nephrol. 10: 25–36, 2014
- Jayne DRW, Bruchfeld AN, Harper L, Schaier M, Venning MC, Hamilton P, Burst V, Grundmann F, Jadoul M, Szombati I, Tesař V, Segelmark M, Potarca A, Schall TJ, Bekker P, Group for the CS: Randomized Trial of C5a Receptor Inhibitor Avacopan in ANCA-Associated Vasculitis. J. Am. Soc. Nephrol. ASN.2016111179, 2017