[A case of gastric cancer associated with systemic lupus erythematosus and nephrotic syndrome].

A 72-year-old man with a complaint of lower limb edema was admitted to our hospital. Investigations revealed anemia, a decreased serum albumin level (1.7g/dl), and an increased urinary protein volume (7.4g/day), leading to a diagnosis of nephrotic syndrome. He also tested positive for anti-nuclear antibody and anti-DNA antibody, fulfilling the criteria for systemic lupus erythematosus (SLE). Endoscopy revealed type 2 advanced gastric cancer at the greater curvature of the antrum of the stomach. We performed distal gastrectomy and an open right renal biopsy without preoperative treatment. Histopathological examination of the resected stomach specimens revealed adenocarcinoma. Immunohistochemistry of the kidney specimen suggested membranous lupus nephritis. After surgery, his urinary protein volume gradually decreased and lower limb edema improved in the absence of any specific treatment for nephrotic syndrome or SLE.