Refractory myeloperoxidase-antineutrophil cytoplasmic antibody-positive retroperitoneal fibrosis: a case report

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Background Myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-positive retroperitoneal fibrosis (RPF) is an extremely rare condition. Currently, there is no consensus on diagnostic criteria or optimal treatment strategies for autoimmune disease-associated RPF. Herein, we report a case of refractory MPO-ANCA-positive RPF. Case presentation A patient presented to the Department of Rheumatology and Immunology with abdominal pain and was diagnosed with ANCA-positive RPF following comprehensive evaluation. Initial treatment with glucocorticoids combined with cyclophosphamide (CTX) demonstrated limited efficacy, and the patient developed a likely glucocorticoid-related adverse event, namely, vertebral compression fracture. Rituximab (RTX) was subsequently added to the regimen. This treatment adjustment resulted in a significant regression of RPF lesions. Conclusions For refractory ANCA-positive RPF, combination therapy with CTX and RTX represents a potential therapeutic option and may reduce reliance on glucocorticoids.