The patient was a 56-year-old man who presented with abnormal urinalysis findings of over one month’s duration. Serological tests revealed an elevated serum free light chain κ/λ ratio, and immunofixation electrophoresis detected an IgG-κ monoclonal band. Renal biopsy demonstrated membranous nephropathy, with electron-dense deposits observed in the subepithelial space and mesangium on electron microscopy. Immunofluorescence confirmed glomerular deposits of IgG_1/IgG₃-κ. Based on clinical manifestation, bone marrow flow cytology, and lymph node pathology, the patient was diagnosed with small lymphocytic lymphoma (SLL), and membranous nephropathy with light chain-restricted deposition (IgG₁/IgG₃-κ) secondary to SLL. After receiving obinutuzumab treatment, the patient’s proteinuria partially remitted, the lymph nodes significantly shrank, and clinical remission was achieved.

TAFRO syndrome is an idiopathic systemic inflammatory disease that overlaps with idiopathic multicentric Castleman disease (iMCD). The clinical features of TAFRO syndrome include thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis/renal insufficiency (R) and organomegaly (O). The paper reports a special clinical subtype of iMCD—TAFRO syndrome in a patient, manifested as multiple-system involvement including serous effusion (ascites), fever, thrombocytopenia, anemia, multiple lymphadenopathies, pancreatitis and renal insufficiency. Bone marrow biopsy pathology showed active bone marrow hyperplasia. Renal biopsy revealed renal thrombotic microangiopathy, acute renal tubular interstitial injury combined with chronic lesions. Lymph node biopsy demonstrated lymphoproliferative lesions consistent with Castleman disease (hyaline vascular type). Following diagnosis, glucocorticoids, tacrolimus, rituximab and lenalidomide were administered, resulting in significant symptomatic improvement: ascites disappeared, and urinary findings, erythrocyte counts, renal function and hematological indexes normalized. The paper describes the patient's clinical manifestations, diagnosis and treatment process, and prognosis, and reviews relevant literature, to improve clinicians' understanding of this rare disease.

TAFRO syndrome is an idiopathic systemic inflammatory disease that overlaps with idiopathic multicentric Castleman disease (iMCD). The clinical features of TAFRO syndrome include thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis/renal insufficiency (R) and organomegaly (O). The paper reports a special clinical subtype of iMCD—TAFRO syndrome in a patient, manifested as multiple-system involvement including serous effusion (ascites), fever, thrombocytopenia, anemia, multiple lymphadenopathies, pancreatitis and renal insufficiency. Bone marrow biopsy pathology showed active bone marrow hyperplasia. Renal biopsy revealed renal thrombotic microangiopathy, acute renal tubular interstitial injury combined with chronic lesions. Lymph node biopsy demonstrated lymphoproliferative lesions consistent with Castleman disease (hyaline vascular type). Following diagnosis, glucocorticoids, tacrolimus, rituximab and lenalidomide were administered, resulting in significant symptomatic improvement: ascites disappeared, and urinary findings, erythrocyte counts, renal function and hematological indexes normalized. The paper describes the patient's clinical manifestations, diagnosis and treatment process, and prognosis, and reviews relevant literature, to improve clinicians' understanding of this rare disease.