Cryofibrinogen-associated glomerulonephritis accompanied by advanced gastric cancer.

We had a 72-year-old man with advanced gastric cancer, poorly differentiated adenocarcinoma, receiving chemotherapy with S-1 (tegafur, gimeracil, and oteracil potassium) plus oxaliplatin. Ascites developed despite remission of gastric cancer and metastasis. Given no malignant cells in ascites, leg edema, renal impairment, hypoalbuminemia, and massive proteinuria, we diagnosed as nephrotic syndrome with microscopic hematuria. Renal biopsy showed membranoproliferative glomerulonephritis with no deposition of immunoglobulins and complements. Of note, electronic microscopy found organized deposits with microtubular structures in the glomerular capillary lumens and subendothelial spaces. The liquid chromatography-tandem mass spectrometry method detected fibrinogen alpha chain, beta chain, gamma chain, and fibronectin, and we eventually diagnosed cryofibrinogen-associated glomerulonephritis. Cryofibrinogen was not detected in plasma. He was expired at 5 months following renal biopsy due to the progression of refractory nephrotic syndrome. In addition to the detailed assessment of specifically organized deposits, the analysis using liquid chromatography-tandem mass spectrometry method is useful to diagnose cryofibrinogen-associated glomerulonephritis. We should consider cryofibrinogen-associated glomerulonephritis as a differential diagnosis when the patients with malignancy showed abnormal urinalysis and renal impairment, though it is a rare disease.