Is It Coincidence or Consequence for a Case with Antiphospholipid Antibody Syndrome Overlapping SLE to Develop an Immune Complex Nephropathy Followed by a Nonimmune Complex Podocytopathy?

Antiphospholipid antibody syndrome (APS) may occur in a primary form or in association with SLE and seldom presents with nephrotic syndrome (NS). We present a case with APS who developed recurrent NS 6 years apart. The first episode of NS occurred with biopsy findings consistent with lupus nephritis (LN) class V (membranous) with no clear evidence of SLE, and responded to a remission with steroids and MMF. On the 2nd episode, the biopsy revealed negative immunofluorescent (IF) study for immune complexes and EM findings of complete effacement of foot processes and acellular debris in thickened capillary walls, compatible with healed previous episode of membranous LN and minimal change disease (MCD), a nonimmune complex podocytopathy. The 2nd episode responded to a partial remission, primarily with a short-term steroid therapy, and subsequently developed serologic evidence of SLE. Now there is growing evidence that a subset of SLE patients with NS are found to have MCD, likely due to podocyte injury caused by nonimmune complex pathway, called lupus podocytopathy. In LN, serial kidney biopsies often show transformation from one to another class of immune complex-induced glomerular lesions; however there are rare reports describing transformation of an immune complex to a nonimmune complex LN. Since the pathogenic mechanism of lupus podocytopathy is not delineated, and so far there are no reports on transformation of membranous LN, an immune complex nephropathy, to a nonimmune complex lupus podocytopathy, it still remains as a question whether our case with APS overlapping SLE had a concomitant membranous LN and lupus podocytopathy, or consequential membranous LN and lupus podocytopathy 6 years apart.