An Unanticipated Case of C1Q Nephropathy Diagnosed after Re-biopsy

Introduction: C1q nephropathy is a rare, poorly understood glomerulonephropathy that typically occurs in older children or younger adults. It is characterized by C1q protein deposition in the mesangium without features of Systemic Lupus Erythematosus (SLE). Treatment generally consists of immunosuppressants however specific regimens are not well established. We present a case of a patient with new onset edema and proteinuria with initial renal biopsy suggesting Minimal Change Disease (MCD) vs Focal Sclerosing Glomerulonephritis (FSGS) and repeat biopsy confirming C1Q nephropathy. Case Description: A 39 y/o Hispanic female presented to the hospital for 5 days of bilateral edema from her ankles to her abdomen. Creatinine was 0.5 mg/dL. Urinalysis showed 4+ protein and trace blood without RBCs. A spot urine Protein:Cr was 8.9 g/g and albumin was 2.2 g/dL. Secondary workup for autoimmune and infectious glomerular etiologies revealed high SS-A and SS-B. Renal biopsy showed one glomerulus with segmental sclerosis, diffuse podocyte effacement, and prominent mesangial/paramesangial deposits with no glomeruli on immunofluorescence. Her proteinuria improved to 1.3 g/g after a 4 week prednisone taper for presumed MCD vs FSGS, but increased to 5.3 g/g off steroids. Rheumatology follow-up determined she did not have SLE. An 8 week steroid taper improved her proteinuria to 0.35 g/g, but worsened to 7.6 g/g after several months off steroids. A repeat renal biopsy revealed FSGS with likely C1q nephropathy variant with 2+ granular staining with C1q. Steroids were resumed. Rituximab and mycophenolate were considered, however lack of insurance delayed treatment. Despite continued steroids, her proteinuria increased to 6.7 g/g and she eventually started mycophenolate. She is currently improving with 5mg prednisone, mycophenolate, and tacrolimus. Her most recent proteinuria was 0.89 g/g and Cr was 0.55 mg/dL. Discussion: This case highlights the importance of considering C1Q nephropathy as part of the differential with presentations similar to MCD and FSGS as well as the value of considering a second biopsy with recurrent relapses. Moreover, the events of this case span over four years due to difficulties in obtaining specialty appointments, affordable medications, and consistent care. This case also highlights the detriments of inaccessibility to healthcare when attempting to treat nephropathies in a timely manner.