Decrease of proteinuria in a patient with adult‐onset Still's disease and glomerulonephritis after anti‐TNFα therapy

We report the case of a 41‐year‐old man diagnosed with Still's disease. Multiple disease‐modifying anti‐rheumatic drug (DMARD) therapies failed to induce disease remission or to prevent progressive joint destruction. The man presented with active arthritis and classical Still's rash accompanied by fever. Anti‐tumour necrosis factor‐α (TNFα) therapy was planned but during the medical check‐up prior to the biological therapy, renal insufficiency with marked proteinuria (PU) was discovered. With PU of 912 mg/24 h a renal biopsy was performed and a histopathological evaluation revealed the diagnosis of a residual mesangio‐proliferative immunocomplex‐based glomerulonephritis (GN). After excluding contraindications, infliximab therapy was initiated and a good response of the arthritis was documented after 6 weeks. A significant decrease in PU (279 mg/24 h) was noted after the third infliximab infusion. Because of an allergic reaction during the fifth dose, the infliximab was discontinued. During the time frame ...