Diagnosis and treatment of secondary nephrotic syndrome with rash as the first symptom: a case report.

Background: Membranous nephropathy (MN) is a common type of nephrotic syndrome (NS) in adults, accounting for about 20–30% of cases. Although secondary to specific factors, the coexistence of MN and mantle cell lymphoma (MCL) has been scarcely reported in clinical literature. Case presentation: A 59-year-old Chinese male was admitted to the hospital with a generalized pruritic rash with bilateral lower extremity edema, which did not improve significantly after symptomatic treatment. He had undergone renal biopsy, and the diagnosis was thought to be secondary MN (SMN), therefore, we did a lymph node biopsy on the patient and found that MN was complicated with MCL. Soon after, the patient was admitted to the hematology department for a BR chemotherapy regimen (composed of bendamustine 90 mg/m² BSA (body surface area), rituximab 375 mg/m² BSA and dexamethasone 5 mg), and during the post-treatment follow-up, both his symptoms and renal function improved. Conclusions: The mechanism underlying the combination of SMN and MCL remains elusive and exceedingly rare, consequently often overlooked in clinical practice. This case serves to offer valuable clinical insights for diagnosis and treatment, while emphasizing the pivotal role of renal pathology in clinical assessment. [ABSTRACT FROM AUTHOR]