Diagnostic Dilemma: Lupus Podocytopathy

Introduction: Lupus podocytopathy (LP) is a rare manifestation in patients with systemic lupus erythematosus (SLE), commonly presenting with nephrotic syndrome. It accounts for about 1% of lupus nephritis biopsies and is even more uncommon in elderly males. Before 2002, cases with SLE along with minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS) were reported and considered separate entities, raising the question of whether podocytopathy was a direct result of active SLE and lead to the term "lupus podocytopathy." Hu et al.'s 2016 case series further clarified our understanding of this condition. Case Description: An 85-year-old male with a medical history of hypertension, heart failure with preserved ejection fraction, sarcoma of the left thigh status post-amputation, and severe aortic stenosis presented with hypervolemia. Laboratory tests revealed an increase in serum creatinine from 0.8 mg/dL to 3.5 mg/dL. Urinalysis was bland, with a urine protein-creatinine ratio (UPCR) of 13 g/g and a urine albumin-creatinine ratio (UACR) of 9.24 g/g. Serum albumin was markedly reduced at 1.6 g/dL. Serologic workup indicated hypocomplementemia, a high titer of antinuclear antibody, and positive anticardiolipin antibody. The patient met the 2019 EULAR/ACR classification criteria for SLE, scoring 10 points. Renal biopsy revealed acute tubular necrosis with minimal mesangial and endothelial hypercellularity, along with PAS-positive reabsorption droplets, suggesting MCD. Immunofluorescence (IF) was negative. High-dose corticosteroids were initiated empirically for suspected LP. Electron microscopy (EM) confirmed diffuse foot process effacement (DFE) without immune complex deposition, consistent with the MCD variant of LP. Following treatment, the patient's hypervolemia resolved, serum creatinine improved to 1.2 mg/dL, and the UPCR decreased to 8 g/g after two weeks. A gradual steroid taper was planned over 4–8 weeks based on the outpatient response. Discussion: Lupus podocytopathy in patients with SLE is diagnosed by biopsy findings of either MCD variant or FSGS lesions, with or without mesangial proliferation. IF and EM show no deposits but DFE. The MCD variant typically has a favorable prognosis over the FSGS variant. Maintenance therapy with glucocorticoids and additional immunosuppressives has been associated with a reduced relapse rate. Prospective trials are needed to further validate treatment efficacy.