Concurrent minimal change disease and retroperitoneal liposarcoma successfully treated by tumor resection and steroid therapy.

A 54-year-old Japanese woman developed simultaneous abdominal distension and bilateral leg edema. Her medical history and results of periodic medical check-up were unremarkable. Blood tests revealed severe hypoproteinemia and acute kidney injury, and urinalysis revealed 4+ proteinuria and 2+ hematuria. Abdominal computed tomography revealed a large intra-abdominal mass with fat tissue density. She underwent emergency tumor excision, splenectomy, and distal pancreatectomy. However, hypoproteinemia and acute kidney injury worsened. Therefore, she was transferred to the nephrology division for confirmation of diagnosis and for treatment of acute kidney injury and nephrotic syndrome. We conducted percutaneous kidney biopsy and diagnosed minimal change disease (MCD). Intravenous prednisolone was started, and heavy proteinuria and systemic edema were gradually alleviated. She achieved complete remission 2 months later, and oral prednisolone was tapered. Histopathological diagnosis of abdominal tumor was dedifferentiated liposarcoma of retroperitoneal origin. Immunohistochemical staining revealed strong expression of vascular endothelial growth factor in the tumor cells in the dedifferentiated component. Currently, her clinical course is stable without recurrence of liposarcoma and nephrotic syndrome. MCD develops in patients with Hodgkin's lymphoma, solid organ cancers, hematological malignancies, and thymoma, whereas concurrent MCD and liposarcoma are rare. Remission of nephrotic syndrome and normalized kidney function induced by steroid therapy are important for better management of patients with malignancy.