Minimal Change Nephrotic Syndrome Complicated by Classical Hodgkin Lymphoma During Prolonged Rituximab Maintenance Therapy: A Case Report.

Minimal change nephrotic syndrome (MCNS) has traditionally been linked to T-cell dysfunction; however, mounting evidence suggests that B-cell-mediated mechanisms also play a significant role. Rituximab (RTX) is increasingly utilized as maintenance therapy for recurring MCNS, yet its extended safety profile remains uncertain. In this study, we report a rare case of MCNS complicated by classical Hodgkin lymphoma (cHL) that emerged during prolonged RTX maintenance therapy. A 23-year-old woman with relapsing MCNS achieved sustained remission with RTX maintenance therapy. Following 13 RTX courses, the patient developed nodular sclerosis-type cHL and attained complete remission with A + AVD chemotherapy (adriamycin, brentuximab vedotin, vinblastine, and dacarbazine). Despite successful chemotherapy for cHL, the patient relapsed with nephrotic syndrome featuring significant proteinuria (8.43 g/day) as RTX efficacy declined. This clinical progression illustrates a close temporal link between RTX effect loss and disease recurrence, supporting the contributory role of elevated peripheral CD19+ B cells in MCNS relapse. Although sustained B-cell-targeted therapy seems effective for prolonged disease management, the exceedingly rare incidence of cHL during extended RTX maintenance in this patient highlights the importance of vigilant long-term safety monitoring with prolonged B-cell depletion.