Rituximab in remission induction and maintenance therapy for microscopic polyangiitis associated with gastric cancer: A case report.

We herein report a case of a patient with gastric cancer-associated microscopic polyangiitis (MPA) who was treated with combination glucocorticoids and rituximab (RTX) for remission induction and maintenance, and finally to discontinue glucocorticoids without recurrence of gastric cancer or MPA in a year. A 69-year-old man was suspected of having MPA because of fever, high C-reactive protein levels, neuritis, and a high titer of myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA). Upper gastrointestinal endoscopy indicated early-stage gastric cancer, for which he underwent surgery preceded by immunosuppressive therapy for vasculitis. Histopathological images showed vasculitis in the vicinity of the cancerous tissue, suggesting an association between gastric cancer and vasculitis. Postoperatively, fever and inflammatory response improved, but MPO-ANCA increased further and the patient developed alveolar hemorrhage. He resulted in remission with high-dose glucocorticoids and RTX, and he received maintenance therapy with RTX without additional immunosuppressive agents. After 1 year of treatment, he was able to discontinue glucocorticoids without recurrence of gastric cancer or vasculitis. There is no established treatment for malignancy-associated vasculitis other than glucocorticoids. Although more cases need to be accumulated in the future, RTX is expected to be useful in malignancy-associated vasculitis.