Approximately 5% of patients with IgA nephropathy (IgAN) exhibit mild mesangial lesions with acute onset nephrotic syndrome and diffuse foot process effacement representative of minimal change disease (MCD). It is not clear whether these unusual cases of IgAN with MCD (IgAN-MCD) are variant types of IgAN or coincidental deposition of IgA in patients with MCD. In a retrospective multicenter cohort study of 18 hospitals in Korea, we analyzed 46 patients with IgAN-MCD. Patients with endocapillary proliferation, segmental sclerosis, and crescent were excluded, and the clinical features and prognosis of IgAN-MCD were compared with those of pure MCD. In addition, we performed galactose-deficient IgA1 (KM55) staining to characterize IgAN-MCD. Among the 21,697 patients with glomerulonephritis enrolled in the database, 46 patients (0.21%) were diagnosed with IgAN-MCD, and 1610 patients (7.4%) with pure MCD. The 46 patients with IgAN-MCD accounted for 0.6% of primary IgAN patients (n = 7584). There was no difference in prognosis between patients with IgAN-MCD and those with only MCD. IgA and KM55 showed double positivity in all patients with IgAN-MCD (n = 4) or primary IgAN (n = 5) under double immunofluorescent staining. However, in four patients with lupus nephritis, mesangial IgA was deposited, but galactose-deficient-IgA1 (Gd-IgA1) was not. These findings suggest that IgAN-MCD is a dual glomerulopathy in which MCD was superimposed on possibly indolent IgAN. We confirmed by KM55 staining that IgAN-MCD is true IgAN, enabling better characterizations of the disease. Furthermore, IgAN-MCD shows a good prognosis when treated according to the usual MCD treatment modality.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a complex systemic autoimmune disease characterized by small vessel vasculitis. Typically, the relapse rate is lower in patients with end-stage kidney disease (ESKD) than in those with chronic kidney disease, prior to dialysis. Here, we report a rare case of multi-organ relapse in a patient with myeloperoxidase (MPO)-AAV who underwent hemodialysis following coronavirus disease 2019 (COVID-19). A man in his 70s with type 2 diabetes and hypertension was undergoing maintenance hemodialysis for ESKD resulting from MPO-AAV glomerulonephritis. Following severe acute respiratory syndrome coronavirus 2 infection, the patient was hospitalized for persistent nausea and vomiting. No significant findings were observed, including in endoscopy. However, the patient experienced severe symptoms that hindered oral intake and was refractory to pharmacological therapy. Additionally, despite receiving antibiotics and antituberculosis treatment, the patient experienced persistent unexplained pleural effusion. Moreover, the patient’s level of consciousness rapidly deteriorated during hospitalization. Although C-reactive protein levels and MPO-ANCA titers were elevated, no evidence of infection was detected on brain imaging or cerebrospinal fluid analysis. Therefore, we diagnosed this case as a relapse of AAV and promptly administered methylprednisolone pulse therapy and rituximab. Subsequently, all aforementioned symptoms in the patient improved, and the current ANCA levels remain negative. Thus, the relapse of AAV after COVID-19 is rare; however, it can present in several ways in patients undergoing dialysis. Therefore, clinicians should closely monitor ANCA titers and subtle symptoms, even in patients with dialysis-dependent AAV.