Microscopic polyangitis complicating double carcinoma of the stomach and duodenum: improvement after the resection of these carcinomas.

A 74-year-old woman developed fever, numbness of legs and glomerulonephritis. Antineutrophil cytoplasmic autoantibodies specific for myeloperoxidase (MPO-ANCA) were positive in her serum, and she presented with acute renal failure. She was also simultaneously diagnosed as having both gastric and duodenal cancers. Complete resection of both cancers and renal biopsy was performed. Some glomeruli showed cellular crescentic changes, while submucosal necrotizing vasculitis of small vessels was noted adjacent to the gastric cancer. A diagnosis of microscopic polyangitis was made. After the operation, the patient's fever, renal failure and microscopic hematuria improved and obvious reductions in her serum soluble receptors of interleukin 2 values and MPO-ANCA titer were observed without any further treatment. However, the patient's proteinuria, cylinduria, and elevated C-reactive protein persisted; these findings eventually resolved after treatment with 30 mg of prednisolone daily. An immunohistochemical analysis showed that CD8 T lymphocytes had infiltrated both the carcinomas and the renal lesions. Our case suggests that CD8 T cells induced as part of an immune response against carcinoma may play a pathologic role in ANCA-positive paraneoplastic syndrome.