Clinical case of membranous nephropathy in a patient with IgG4-related disease

IgG4-related disease (IgG4-RD) currently is considered as a chronic fibroinflammatory immune-mediated multisystemic condition of unidentified etiology, which can imitate a wide range of malignant, infectious, rheumatologic, and other diseases. It can affect almost any organ system in the body synchronously or sequentially, but the most often affected are the pancreas, hepatobiliary tract, periorbital structures, salivary glands, kidneys, and lymph nodes. The most frequent renal manifestations of IgG4-RD is IgG4-related tubulointerstitial nephritis. Membranous nephropathy is the most common glomerular disease accompanied by IgG4-RD. Regardless of the organ localization, patients with IgG4-RD are characterized by elevated serum IgG4, but this laboratory abnormality is not specific and can be changed in other diseases. In all suspected cases of IgG4-RD the diagnosis should be confirmed by histological examination. Characteristic pathologic features include diffuse or focal lymphoplasmacytic infiltration with prominent IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis. Patients with IgG4- RD usually have an excellent clinical response to glucocorticoids, but relapse rates after steroid withdrawal are high, which may require additional use of immunosuppressants or rituximab. Due to the low prevalence and multitude of clinical manifestations the disease often remains underdiagnosed on time. This case report describes middle-aged patients with a history of chronic recurrent pancreatitis complicated by the nephrotic syndrome. Kidney biopsy showed membranous nephropathy and diagnosis IgG4-RD with multiorgan involvement was made. Partial remission was achieved on corticosteroid therapy. The presented case clearly demonstrates the difficulties of diagnosis and treatment of IgG4-RD. IgG4-related membranous nephropathy should be included in the differential diagnosis for patients with nephrotic syndrome accompanied by multiorgan dysfunction.