Steroid-resistant nephrotic syndrome secondary to primary focal segmental glomerulosclerosis and smoldering multiple myeloma

Podocytopathy in patients with monoclonal gammopathy: three patients and literature review

BACKGROUND

Renal manifestations of monoclonal gammopathies are of increasing interest among nephrologists. Typical manifestations include light chain cast nephropathy, amyloidosis or renal damage mediated by monoclonal immunoglobulin deposition. Podocytopathies in the setting of an underlying monoclonal gammopathy constitute a rare manifestation of these diseases and, although being described in the literature, remain a challenge since most data derive from case reports.

METHODS

A retrospective review of the clinical data of Hospital del Mar and Hospital Vall d'Hebron was performed to identify patients with minimal change disease (MCD) or focal and segmental glomerulosclerosis (FSGS) in the setting of neoplasms that produce monoclonal (M) protein. Additionally, a literature review on this topic was performed. This study aims to describe the clinical characteristics and outcomes of these patients.

RESULTS

Three patients were identified to have podocytopathy and monoclonal gammopathy between the years 2013 and 2020. All three were males and  >65 years of age. Two patients were diagnosed with MCD and one patient was diagnosed with FSGS. All patients underwent a kidney biopsy and light and electron microscopic studies were performed. The underlying causes of monoclonal gammopathy were multiple myeloma in two cases and Waldeström macroglobulinemia in one case. Two patients developed nephrotic syndrome during the follow-up. All patients were under active hematological treatment. One patient presented a complete remission of proteinuria whereas the other two presented a partial remission.

CONCLUSIONS

Podocytopathies may infrequently be found in patients with monoclonal gammopathies. Patients with overt glomerular proteinuria and hematological disorders with M protein should undergo a kidney biopsy for prompt diagnosis and to specify a prognosis. In addition, further study on this matter must be done to understand the pathophysiology and treat these patients appropriately.

Multiple myeloma with a previous diagnosis of focal segmental glomerulosclerosis: A case report and review of the literature

The presentation of focal segmental glomerulosclerosis (FSGS) and multiple myeloma (MM), either together or in succession, is extremely rare. Only nine studies have previously reported this poorly understood association. The present study reports the case of a 45-year-old male with FSGS that was diagnosed by a renal biopsy performed for nephrotic syndrome (NS). The patient was admitted to the Chinese People's Liberation Army General Hospital one year later with a fever, anemia, unresolved NS and renal insufficiency. The patient was diagnosed with MM and a renal biopsy was repeated, the results of which suggested renal amyloidosis. The MM was treated with three cycles of vincristine, doxorubicin and dexamethasone chemotherapy. A review of the literature indicated that monoclonal gammopathy may lead to FSGS. It suggested that FSGS patients who are >40 years old should be routinely screened for plasma cell proliferative disorders to guide the treatment, determine a prognosis, achieve primary disease remission and avoid end-stage renal disease.