A case of minimal change nephrotic syndrome complicated by Kimura disease treated with rituximab

Kimura disease (eosinophilic granuloma of the soft tissue) is a benign granulomatous disease complicated by nephrotic syndrome. Herein, we report a case of recurrent minimal change nephrotic syndrome (MCNS) complicated by Kimura disease that was successfully treated with rituximab. A 57-year-old man presented to our hospital with relapsed nephrotic syndrome with worsening swelling of the right anterior ear and elevated serum IgE. MCNS was diagnosed on renal biopsy. Treatment with 50 mg of prednisolone rapidly placed the patient in remission. Therefore, RTX 375 mg/m² was added to the treatment regimen, and steroid therapy was tapered. Early steroid tapering was successful, and the patient is currently in remission. In this case, the nephrotic syndrome flare-up was accompanied by worsening Kimura disease. Rituximab reduced the worsening of symptoms related to Kimura disease, including head and neck lymphadenopathy and elevated IgE levels. Kimura disease and MCNS may share a common IgE-mediated type I allergic condition. Rituximab effectively treats these conditions. In addition, rituximab suppresses Kimura disease activity in patients with MCNS, enables early tapering of steroids, and reduces the total dose of steroids.