ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: PO2215

A De Novo Case of C1q Nephropathy in a Renal Allograft

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Appelbaum, Zachary, George Washington University Medical Faculty Associates, Washington, District of Columbia, United States
  • Jagadeesan, Muralidharan, George Washington University Medical Faculty Associates, Washington, District of Columbia, United States
  • Melancon, Joseph Keith, George Washington University Medical Faculty Associates, Washington, District of Columbia, United States
  • Shankaranarayanan, Divya, George Washington University Medical Faculty Associates, Washington, District of Columbia, United States
Introduction

C1q nephropathy (C1qN) is a rare idiopathic glomerulopathy that is characterized by mesangial C1q deposition in the absence of systemic lupus erythematosus or membranoproliferative glomerulonephritis. Clinical manifestations vary, but can include proteinuria, hematuria, and renal dysfunction. C1qN is not usually responsive to corticosteroids and outcomes are poor for most patients. We describe a de novo, but clinically silent case of C1qN in a renal allograft incidentally detected on surveillance biopsy.

Case Description

A 20 year old male, with history of end stage renal disease secondary to congenital renal hypoplasia, on maintenance tacrolimus, mycophenolate mofetil, and oral prednisone, underwent a surveillance biopsy 1 year after a deceased donor kidney transplantation. Laboratory studies revealed a baseline serum creatinine of 1.7 mg/dL and a spot urine protein to creatinine ratio of 258 mg/g. Urinalysis did not show hematuria and the rheumatologic workup was unremarkable. Light microscopy revealed minimal mesangial hypercellularity without endocapillary proliferation. Immunofluorescence microscopy demonstrated granular mesangial staining for C1q with positive staining for IgG, IgM, C3, C4, and kappa and lambda light chains. Electron microscopy revealed mesangial and paramesangial electron-dense immune deposits.

Discussion

Unlike other C1qN cases described in the literature, our patient did not have evidence of an underlying autoimmune disease or viral infection. Renal biopsy demonstrated positive immunofluorescence staining of IgG, IgM, C3, C4, and kappa and lambda light chains, in addition to C1q. Moreover, there was no evidence of proteinuria, hematuria, or renal dysfunction. One question that arises is whether this patient, with a history of congenital renal hypoplasia, was susceptible to developing an autoimmune process that was otherwise being masked by immunosuppression. This case emphasizes the following: (1) further research is needed to determine the frequency and length of monitoring of de novo C1qN in renal transplant recipients, and (2) further research is needed to determine the optimal therapeutic regimen.