Rare Biopsy Findings of IgA and C3 on Immunofluorescence in ANCA-Associated Vasculitis

Introduction: ANCA associated vasculitis includes GPA, MPA and renal limited vasculitis. It is a severe pauci-immune vasculitis with high mortality which requires prompt management. Some cases have been reported with immune deposits and glomerular C3 deposits. Such cases are now increasingly recognized and associated with worse outcomes. Very rarely there can also be glomerular IgA deposits. Immune deposits of C3 and IgA are also seen in IRGN and IgA nephropathy which can also be associated with ANCA positivity. This poses a diagnostic challenge which requires ruling out infections as immunosuppressives can be detrimental in such cases. Case Description: 55-year-old male admitted with recurrent upper respiratory symptoms started 2 months ago. He was initially treated with antibiotics for otomastoiditis. CT chest revealed cavitary lung lesions and was started on appropriate antibiotics for pneumonia. Admission wbc 18 10*3/UL, creatinine (Cr) 1 mg/dl and worsened to 9mg/dl, Positive ANCA 1:80 AI , PR3 30 U/ml, CRP 130mg/L. Anti GBM negative. Kidney biopsy revealed necrotizing and crescentic glomerulonephritis with leukocytoclastic vasculitis, C3/IgA-codominant glomerulonephritis, likely infection-related, mild to moderate interstitial fibrosis and tubular atrophy. Rheumatology and ID were consulted. Any active infection was ruled out before initiating patient on immunosuppressive regimen. He received cyclophosphamide, steroids with taper and transition to Avocapan, PLEX and rituximab. Renal function remained stable but had to be dialyzed once, Clinically, he improved and respiratory symptoms resolved. Discussion: Our case is unique in which a multispecialty approach was used for management. Although Overlap of ANCA with IRGN possible,this patient received multiple courses of antibiotics during and prior to this admission with no improvement favoring ANCA vasculitis as primary diagnosis.There are no previous cases reported with PR+ ANCA vasculitis with glomerular C3 and IgA deposition. Clinical history, physical examination and characteristic biopsy findings were used together to promptly start management of ANCA associated vasculitis with stabilization of renal function and improvement in respiratory symptoms. A case like this poses a diagnostic challenge for physicians as initiating the appropriate treatment in a timely fashion is extremely important for a patient’s recovery.