Systemic lupus erythematosus combined with Castleman disease: a case report.

Systemic lupus erythematosus (SLE), a multisystemic autoimmune disorder, carries an increased risk of lymphoproliferative diseases, with overlapping clinical features often complicating diagnostic differentiation. We describe a 54-year-old woman with established SLE involving the skin, joints and kidneys (previously managed with prednisone, cyclophosphamide and hydroxychloroquine). Following self-discontinuation of prednisone treatment, the patient developed a disease flare manifesting as a labial rash and proteinuria. Renal histopathology confirmed persistent class V lupus nephritis. Computed tomography (CT) identified left axillary lymphadenopathy, with subsequent excisional biopsy revealing features diagnostic of Castleman disease. The coexistence of SLE and Castleman disease (CD) is relatively rare. Targeted immunosuppressive therapy with tacrolimus (TAC) and mycophenolate mofetil (MMF) resulted in clinical stabilization within 3 months of treatment initiation. Proteinuria decreased from 1.35 g/24 h to 0.24 g/24 h, with a concomitant reduction in lymph node size. Clinical improvement even in the absence of glucocorticoid induction therapy offers valuable insights for clinicians.