Podocytic infolding glomerulopathy: two new cases with connective tissue disease and literature review

Podocytic infolding glomerulopathy (PIG) is a newly proposed disease entity, and only 29 cases have been reported worldwide so far, characterized by microspheres or microtubular structures or both associated with podocytic infolding into the glomerular basement membrane (GBM) on electron microscopy. We present two new cases of PIG with connective tissue disease (CTD), one with primary Sjögren’s syndrome and the other with systemic lupus erythematosus (SLE), and make a systemic review of the literature. In the entire 31 patients of PIG, 24 (77.42%) were women and seven (22.58%) were men, with an average age of 41.2 ± 15.2 (ranging from 14 to 79) years old. Almost two-thirds of patients (67.74%) were diagnosed with CTD, in which 76.19% were SLE. All patients presented with proteinuria and six (19.35%) patients were accompanied with hematuria. Serum creatinine was elevated in six (19.35%) patients. Pathological findings of all patients were consistent with PIG characteristics, and four patients with repeated renal biopsies further provided profound insights.