A case of systemic lupus erythematosus complicated by TAFRO syndrome-like conditions: analysis of C-X-C motif chemokine ligand 13 and B-cell activating factor dynamics and the efficacy of combination therapy with cyclosporine and belimumab.

TAFRO syndrome, characterised by thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly, is a rare subtype of idiopathic multicentric Castleman disease. Although it is generally not associated with autoimmune diseases, cases with systemic lupus erythematosus have been reported. We report a case of a 52-year-old male with systemic lupus erythematosus complicated by TAFRO syndrome-like conditions. The patient had persistent thrombocytopenia, renal dysfunction, and fluid retention refractory to glucocorticoids, IL-6 inhibitors, and plasma exchange. Treatment with cyclosporine and belimumab was initiated due to a suspicion of aberrant B-cell activation, resulting in a 2-year remission without relapse. To explore the immunological pathogenesis, CXCL13 and BAFF levels were analysed during the clinical course. Despite interleukin-6 (IL-6) inhibitor therapy, C-X-C motif chemokine ligand 13 (CXCL13) levels remained elevated, suggesting the involvement of an alternative regulatory pathway. Both CXCL13 and B-cell activating factor (BAFF) levels decreased after treatment with cyclosporine and belimumab, and this correlated with clinical improvement. CXCL13, which is produced by peripheral helper T cells, promotes aberrant B-cell activation and lymphoid tissue formation. Meanwhile, BAFF supports B-cell survival and autoreactivity, acting alongside CXCL13 to sustain pathological B-cell activity. This case highlights the importance of therapies targeting T-cell and B-cell interactions in certain diseases with refractory conditions. Additionally, monitoring CXCL13 and BAFF may help optimise therapeutic strategies. Combination therapy with cyclosporine and belimumab effectively suppressed both cytokines, achieving sustained disease control. Future studies should utilise cytokine profiling, including CXCL13 and BAFF, to establish personalised therapeutic strategies in cases of systemic lupus erythematosus presenting with TAFRO syndrome-like conditions.