Chapter 32: Vasculitides
A 40-year-old previously healthy woman presents to her primary care physician with night sweats, weight loss, joint pain, and fatigue for 4–5 weeks. On examination she is normotensive and afebrile. Her physical examination is normal. Laboratory testing shows 1+ protein and 30–40 RBC/HPF in the urine, serum creatinine 1.8 mg/dL, ESR 80 mm/hour, urine cultures negative. She is referred to a nephrologist who notes that only a PR3 ANCA is positive at 40 U/mL (negative <0.4 U/mL), with negative antiglomerular basement antibody, negative lupus profile, negative workup for monoclonal gammopathy, and normal complements.
The kidney biopsy is likely to show which of the following immune staining patterns in this patient?
A. Negative immune staining
B. Linear glomerular basement staining
C. Granular staining for IgG, IgA, IgM, C3, and C1q along the capillary wall
D. Staining with IgG and only kappa light chain along the basement membrane
The answer is A. This patient is presenting with features of ANCA-associated vasculitis. Serological tests show only ANCA-positivity. In such patients the kidney biopsy is typically negative or only shows trace staining for antibodies on immunofluorescence (“pauci immune”). The presence of linear glomerular basement (GBM) staining is suggestive of anti-GBM antibody disease. This entity is typically associated with positive anti-GBM antibodies. Similarly, granular staining suggests immune complex disease. The presence of multiple antibodies and complement components being positive suggests lupus nephritis which is unlikely given the negative lupus serologies and complements. The finding of immunoglobulin with only kappa or lambda light chains suggest a monoclonal gammopathy–related kidney disease. In the presence of a negative peripheral monoclonal gammopathy workup, this is unlikely.
A 55-year-old man, with past medical history of coronary artery disease requiring percutaneous intervention is admitted with low-grade fevers and arthralgia for 2 weeks prior to admission. His admission vital signs show normal BP, temperature of 99°F, and physical examination is notable for few petechiae over his lower extremities. His laboratory tests show mild normocytic anemia with hemoglobin 9 g/dL, serum creatinine 2.5 mg/dL, urinalysis with 2+ proteinuria and 10–15 RBC. His serological tests show negative antiglomerular basement membrane antibody, positive myeloperoxidase ANCA, normal complements, and negative lupus serologies. Electrocardiogram shows an old inferior wall infarct. A kidney biopsy is performed and results are pending. After 72 hours of admission, he develops frank hemoptysis and develops respiratory distress requiring intubation. He is noted to have frank blood from his endotracheal tube. His chest X-ray shows diffuse bilateral opacities. His echocardiogram shows wall motion abnormalities in the inferior wall and troponin levels are normal.
What is your next step in management for this patient?
A. Perform a bronchoscopy
B. Start pulse steroids and plasmapheresis