Plasma exchange combined with low-dose rituximab treatment: A case report of severe antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in the elderly.

RATIONALE: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a form of necrotizing vasculitis not mediated by immune complexes, affecting multiple organs. The disease is particularly dangerous in its active stage, with high morbidity and mortality rates, especially among older patients. This study provides a possible treatment for ANCA in the elderly.

PATIENT CONCERNS: An 84-year-old man developed an intermittent cough of unknown etiology in early February 2024, accompanied by hemoptysis, sore throat, dry mouth, arthralgia, fatigue, and occasional low fever. He had a history of chronic kidney disease for over 14 years and had been diagnosed with AAV and ANCA-associated nephritis for more than 9 months.

DIAGNOSES: Laboratory tests in the rheumatology department revealed C-ANCA positivity, proteinase 3 > 200 RU/mL, and an ANCA + proteinase 3 antibody concentration of 2300 IU/L. Serum creatinine concentration had increased to 457 μmol/L↑. Other autoantibodies, including anti-extra nuclear antigen, were negative. Based on these findings and the patient's clinical symptoms, the diagnosis of ANCA-associated vasculitis was confirmed. Imaging revealed patchy and reticular opacities in both lungs, with a butterfly-wing distribution along the hila, accompanied by a small amount of bilateral pleural effusion. Scattered petechiae were observed on both upper limbs.

INTERVENTIONS: The patient's condition was critical and rapidly progressing. He received successive treatments, including methylprednisolone sodium succinate + cyclophosphamide, plasma exchange, blood purification, and repeated small-dose courses of rituximab and belimumab.

OUTCOMES: After 6 months of treatment, the patient achieved clinical, radiological, and serological remission. Hemoptysis stopped, renal function improved, immune status returned to normal, and there was no sign of ANCA recurrence. He was successfully discharged.

LESSONS: Rituximab offers a promising therapeutic option for older patients with chronic kidney disease complicated by AAV. Multiple small-dose rituximab regimens may reduce drug-related side effects, significantly lower treatment costs, and provide an effective, economically viable approach for clinical management.